Traveling from Annecy to Gengenbach

The only suitable route, IMO, is Annecy-Geneva-Bern or Basel-Offenburg-Gengenbach.

You can check connections on the Germans Railways website (DB) and purchase a ticket for Geneva-Gengenbach there. You'll need to get to Geneva from Annecy: bus 272 to the airport (where trains to Bern/Basel originate) is theoretically faster but I'd take the train to Genève Cornavin station, bought on SNCF Connect.

Here's a link to the German Railway website (Deutsche Bahn): https://int.bahn.de/en. Look for the ones with the high-speed trains unless you want to spend a long time traveling. It's still a long route, but you could definitely save some time by taking an ICE train.

Also, on the DB website, you can increase or decrease your transfer time if you like. If you're worried about making a connection, I will say Offenburg is an easy connection, as it's not a big station, so it shouldn't take you a lot of time there, but I'm not familiar with Geneva.

Once you decide on your ticket, I would highly recommend downloading the DB Navigator app. Set up an account either on the website or on the app, and once you have your ticket in there, so you will get notifications if there are any delays or anything like that.

Thank you both so much for taking the time to help me out! I feel more comfortable now and will download the app.

Also, on the DB website, you can increase or decrease your transfer
time if you like.

I would not do that.

If you miss a connection due to a delay you just take the next train.

If you however add a buffer, and your train happens to be on time you will then have to wait at the station, seeing the train leave that you could have taken...

Thank you Wengen for pointing that out - great point.