What does a German Rail Pass actually cover?

What cities are you traveling to?
You might not need to take a ubahn to get where you want to go site seeing

The cities are Osnabrück, Hamburg, Berlin, Dresden, and Munich. I have been to Hamburg before and I know we will need U-bahns there.

I would look at the cost of just buying point to point tickets as there are Super saver fares
It might be cheaper the total of just buying point to point tickets versus committing 270 euros in 2nd class to a 7 day pass or 320 for a 10 day pass.

The DBahn spells out what is covered under terms and conditions for each pass
https://www.bahn.com/en/view/offers/passes/german-rail-pass.shtml

It is a rail pass only. Info here: https://www.bahn.com/en/view/offers/passes/german-rail-pass.shtml
It only covers the train companies listed here: https://www.bahn.com/en/view/mdb/bahnintern/international/redaktion_bahn.com/pdf-datein/pdf_2018/mdb_281723_internationale_passangebote-scic_2017.pdf

In general, it covers S-Bahn, as these are run by DB (usually) under contract to the local transport undertaking. It does not cover U-Bahn (as these are city owned), and equally does not cover trams or buses.

The alternative is one-day passes for each city, or "Länder" tickets which cover all transport in one "Land" (state) for 1 day, taht is all trains, U-Bahn, trams and buses.
These are particular good value for 2 or more people travelling around a "Land" as they are cheaper for more people.
Info here: https://www.bahn.com/en/view/offers/regional/regional-day-tickets.shtml

Travelling between cities you can get large discounts by buying tickets in advance online.

Thanks everyone for the responses!

I suggest to re-think if you want to visit 5 German cities in 9 days. I cannot imagine that this will be fun or a real good experience. For Berlin I recommend 4-5 days alone. Hamburg and Munich 3 days.

You didn't say if that was 9 days including the arrival day and the departure day, or if it was 9 full days plus the 1st and last day. Also, I assume you are not flying into Osnabrück, so you will have 5 days of travel. Even if it was 9 full days, 4 of the days will be used for travel between the 5 cities, leaving only one full day in each city and a bunch of partial days around travel. That's too hectic. I think I would cut the venues to three or less.

Thanks for the feedback, but I’m not changing my vacation. That wasn’t the advice I was looking for. Thanks. There’s a specific reason we are doing things this way.

Additionally, I do not have any full days of travel. Germany is not that big, you guys. Most of the cities are a couple hours apart, tops, excluding Munich. And we are subsequently spending more time there because of the extra travel time. I’ve been to Germany before - I used to live there. I never have been there just to visit, however, which is why I need to know about the passes. Naturally, when I lived there I bought month-to-month passes, so this is unfamiliar territory for me.

The Niedersachsen Ticket covers regional train travel between Hamburg and Osnabrück on the regional trains AS WELL AS local transport like U-bahn, trams, buses... price is under €30 for two.

Berlin - Dresden would be doable on a Quer durchs Land Ticket - €52/2. See details.

I'll join the other two forum members who have advised you that advance-purchase p2p "saver fare" tickets for the other legs - and also for the two I just mentioned - might be worth investigating. Given that you know exactly where you'll be when, with this tight itinerary, the flexibility of railpasses may not be necessary for you.

I think the reason you received advice to change your itinerary was not because interfering with your plans is standard practice - rather, it's just that there was no stated purpose for the really unusual choices.

Thank you very much for the input. Your response was very helpful. I am going these specific places partially because I am visiting friends, and partially because the family members I am traveling with are visiting for the first time and would like to see some tourist attractions and the places of our ancestry.