Autism

SFO has direct flights to Zurich.
Safe travels!

Your questions are quite broad, so I'll just start with some basics.

You want to fly from somewhere in Northern California to Europe, in business class. Well, that shouldn't be difficult, though it will be expensive (business class is), and you'll need to set expectations appropriately.

What's the nearest airport to you with commercial air service?

Most folks prefer (but not everyone is willing to pay for) a non-stop flight. To minimize your time in transit and keep things simple, you are probably going to want to fly via SFO to someplace in Europe (nonstop). If SFO isn't a convenient departure point, you can depart from a smaller airport and connect in SFO, but that adds a stop, MAY add cost, but (perhaps) most significantly, you won't find a real "business class" experience on a short regional flight (smaller planes, domestic...neither have exceptional seats).

You may need to add a connection in Europe, too. That could mean one connection and short flight on a non-impressive plane in a seat that isn't super luxurious; again, the connecting flights are short so are easier to "tough out" in a lesser seat.

If it were me, I'd look for a flight from SFO, nonstop, in a nice comfy business class seat (all business class seats are not equal! - see below) to someplace near your destination (or as close as you can get to it).

The quality of seats on a "business class" ticket can vary tremendously. You need to check carefully what kind of seat you are getting on your specific flight. "Good" business class seats feature a spacious, comfortable individual seat that converts to a flat bed (parts of the flat bed may be a slight bit narrow, eg the foot well may feel more constrained than a night in your bed at home, but it's still so much nicer than coach). Many folks find that European airlines offer better food and service (debatable, often but not always true) than the legacy US airlines. Just make sure the specific seat on your specific flight is one of the good ones (for example, United has some old, disappointing business class seats on some flights, and some new pretty good ones on other flights - so you must check the specific flight/aircraft). Note that you can buy a business class ticket, but any connecting flights will have lesser seats: domestic (US) connections will be in "domestic First" which is generally just a modestly bigger seat; "business class" seats on most intra-European segments are just coach seats with the middle seat (in a row of 3) "blocked" so it's empty. The connecting flights would be short so I don't sweat the details on those. You want to focus your efforts and attention on the long flight (from California to Europe will be roughly 10-11 hours, so that's the flight where the extra comfy seat/bed will make all the difference).

Hope that helps get you started. Good luck.

If you fly into Zurich ( there are direct flights from SFO on Swiss Air and United), there are trains that go to Luzern directly ( no change of trains at the Zurich main station). They run once an hour at 25 minutes after the hour on the current schedule, and take one hour ten minutes for the journey. There are other trains in between, but you must change trains in the Zurich main station, which is huge, and can be confusing.

I use Google Flights to track air prices, and set up price alerts. Last Nov/Dec., we paid $2600 RT for Business Class, SFO- Zurich, and that was one of the lowest Business Class fares I've seen.
Good luck!

The quality of seats on a "business class" ticket can vary
tremendously. You need to check carefully what kind of seat you are
getting on your specific flight.

This is a very important point! Fortunately, Swiss has great business class seats, so go for the direct flight to Zürich.

Q: What resourses are available (we can pay) to get from any Northern California airport to any EU airport in business class (26 yo son has ASD)?

There is ample flights for Northern California to Europe to choose from, but since you mentioned ASD presumable you have some specific concerns. Perhaps if you detail your concerns someone will be able to answer them.....

I agree with Jim. What concerns do you have specifically with your son? noise level, textures etc. That might be helpful to give suggestions.

Norwegian Air flies from San Francisco non-stop to many European cities, their Business Class (they call it something else) is quite affordable. They fly Dreamliners which are very nice, very comfortable.

As Lola notes, Swiss Air has a daily non-stop flight from SFO to Zurich - Swiss Flight 39. Swiss flies a Boeing 777 with three classes of service. United codeshares with Swiss. You can get a no-change train from the Zurich airport to Luzern. Train takes about one hour. Some nice Luzern hotels within a block of the train station.

https://www.seatguru.com/airlines/Swiss_Airlines/Swiss_Airlines_Boeing_777-300ER.php
Business: 60" pitch 20.5" width 62 flat bed seats