Wine in Munich

You will be in Bavaria, and the Northern part of that region has the Franken (Franconia) wine region, known for good quality wines.

I am sure any wine shop will walk you through the options, but I could suggest looking for a decent Sylvaner. It is a white wine made from the Sylvaner grape, tends to be a bit drier than a Reisling, but light and fruity. I think it is a very drinkable wine that would appeal to about anyone who likes white wine, except for the hard core, heavy oak Chardonnay lovers, and even they would likely find it drinkable.

My wife however did have some truly horrible white wine in beer gardens, very cheap (well, cheaply made, the price was a premium), too sweet, so it is a bit buyer beware some places.

I'm not sure where you can get a good wine tasting in Nürnberg, but found the website below. We enjoy Frankenwein and make a trip to Prichsenstadt every year for tasting and buying. Mostly white wines. My Frau likes the sweeter Baucus, Blanc der Noir, Kenner, and Weißburgunder. I stay with the more traditional Müller-Thurgau and Silvaner. I like a good Rotling (Winzer crafted red/white mix) on a summer day. I would say in general all are dry compared to the Mosel Valley.
https://tourismus.nuernberg.de/en/food-drink/nurembergs-specialties/franconian-specialties/franconian-wine/

Unfortunately you probably need a car to get to these:
We buy here every year. Call ahead and you can get great wine tasting. Prichsenstadthttps://www.winzerhof-kessler.de/
Iphofen: https://www.weingut-emmerich.de/
Sometimes in the Handtahl. A small unique region between Mainfranken and the Steigerwald. http://www.weingut-baumann.de/

Not Bavaria, but the South Pfalz has really good wine too and a nice region. We buy the Chardonnay, Riesling and Gelber Muskateller from https://weingut-siegrist.de/

Austrian Wein, try from the Danube River valley Wachau region between Spitz and Krems. All around the Neusiedler See. The town of Rust is nice. One of these days I want to visit the Wein regions around Graz too. Overall the Austrian Grüner Veltliner is a simple choice. 1/3 the vineyards in Austria are Grüner Veltliner.

Long-winded sorry.

In Munich the Pfalzer Weinstube within the Residenz palace (at one time the Bavarian royal family also ruled the Palatinate) has a very wide range of Rhine and Mosel wines by the glass or bottle. All the wines on the list are also available to purchase for off-site consumption at a lower price.

Munich=BEER not wine.
Do German wine in the Rhineland.

No need to travel all over the place to sample wines. Philip provided a good and practical suggestion; Pfalzer Weinstube, and Wein-Moment is close by.

Before going, do a little research on the names in Germany of the styles of wine. I googled "Guide to german wines" and had many hits.

https://germanfoods.org/german-food-facts/german-wine-guide/

This seems a good place to look. German wines tend to be a little sweeter than in the US. I certainly prefer that - US wines are fermented to absolute dryness, which removes some of the "individual grape character" from the wines.

One thing to note: Sometimes people get a little snooty about "sweet wines", as if drinking sweet is a moral failing of some sort. My wife loves sweet wines and we found several in France that were so pleasant to drink. Similarly, in Germany, the spätlese wines are very nice especially served cold in a winery overlooking a river or something.

I have had wine categorized as Spätlese due to the higher sugar content, but in reality dry and 14.5% alcohol due to that high sugar content with fermentation. I can understand a wine tasting in a location other than a Winzer and I understand the travel and time limitations, but to sit with a Winzer tasting their wine and having them tell you about it and answering your questions is something other. It’s always a good time. Sometimes too good a time! Buy the wine you like and enjoy. Germany has more than you might think. Austria too. No wine before it's time... It's time. Glühwein at the Weihnachtsmarkt ist all bad. Try to find one not premade. One of my first stops.

https://www.weingutscout.de/weinregionen-deutschland-karte-weinanbaugebiete/ This does not include the wine region just south of Regensburg near Walhalla.
https://www.austrianwine.com/our-wine/winegrowing-regions

I am guessing from the times you mentioned that you will be back home by Christmas Eve for hosting your company. Germany has some excellent white wines as mentioned by previous responses. Taking the opportunity to do wine tasting while you are in Germany makes excellent sense, but the exact same wines may not be available at home - so deciding on the tastes you like best there will add names to what you decide you need to look for here. But, one can also start with thinking about what is bring cooked for Christmas Eve dinner. Different wines will usually pair best with different foods. Sweeter whites include German Spatlese's and Auslese's or Rieslings, or others like French Viognier's, or Austrian Gruner Veltliners. They go very well with milder fish or lighter chicken recipies, or lighter pork dishes. More 'lemony' wines include Pinot Grigio or Pinot Gris varieties, and I prefer them with most pork dishes. Chardonnay's will be more "buttery" ie. richer and less sweet. They go well with more robust chicken dishes (think gravy) or turkey with all its trimmings. And if you like a wine's taste with your dinner choice then the usual conventions don't actually matter. Have fun with it.

Nick, you are correct. We will be home for Christmas Eve. I traditionally make Feast of the Seven Fishes. It is my intent to find good wine(s) and bring several bottles of each home with me. I do not trust finding them here, after we return.

A good plan. In case you have to turn to local commerce however, Wine Spectator Magazine had an issue on Oregon wines this year and labeled the 2023 Riesling from A to Z Wines in the Williamette Valley to be a top value. I have sampled several and they are very good and very reasonably priced.

Since you have three weeks, I suggest visiting a large, local wine retailer near your home to see what German and Austrian brands they stock. Tell them you are going to travel and want to come home and buy some of your favorites. You can then seek out those brands while traveling to try them. Even if you find a match, you can still bring wine home.

Also, and my German friends can correct me of this, I am of the impressions that Nuremberg is more "wine friendly" when compared to Munich.

We also do Feast of the Seven Fishes as a family tradition on Christmas Eve. We then watch A Muppet Christmas Carol. I will be in Munich and Salzburg around same time as you. I will not be having the wine!

Have a great trip. Enjoy both the beer and the wine...and the fish.