suggested itinerary

Have you looked into drop-off fee for the rental car?

With a week, I would split it between Lake Geneva and Chamonix.

One way rental will add about US$600, if that's in your plan and budget.

You don't have too much time between the places mentioned and the distances to be covered. Did you not have a rough initial idea of things to do between Frankfurt and Geneva?

Look at this sights map of Germany and add your preferences.

Heidelberg, Germany, Strasbourg, France, Baden-Baden, the Black Forest (Triberg and Titisee).

I agree that it will be more expensive to to drive. You might want to find a place to turn your rental car in before you cross over into Switzerland, then take the train to Geneva and decide if you need a car there. And really, as the others have said, a week is not very long to enjoy all the places between, even if you leave Frankfurt right away.

But if you do want to continue with your plans, I would suggest stopping in the Black Forest and visiting some of the more quaint towns there like Gengenbach (my personal favorite), Schiltach, possibly Freiburg im Breisgau. Unless you really want to buy a cuckoo clock, I would skip Triberg as it gets very crowded and touristed, and Titisee can be a bit touristy as well. It does have a lovely lake, but you will have plenty of opportunities to see gorgeous lakes as you head into Switzerland. The charm of the Black Forest, imo, lies in its small villages and towns.

The Vogtsbauernhof (Open-air Folk Museum) is a wonderful must-see museum that is located outside of Gutach (near Gengenbach) where you walk through on a self-guided tour showing authentic and historic farms of how people lived and worked in the Black Forest up to 600 years ago. I absolutely loved it! https://www.vogtsbauernhof.de/en/visit

I don't understand how you will have time for much on that journey--if Geneva environs and Chamonix are the priority, you probably need to fly from Frankfurt.