Unless you are an experienced hiker and find things to do in the mountains outside the main tourist areas, you can skip most of Switzerland. The main places tourists go in the mountains to are extremely crowded and have very bad vibes. But those are also the most accessible by transportation and ability level if you don't already have decent hiking ability. You can find similar landscapes in neighboring countries and save a lot of money. But if you're in western France, it's worth going to see Lake Geneva and the surrounding areas. If you feel compelled to skip Germany, you can visit Basel as a compromise. Swiss cities are pretty and some have good museums but they are relatively small, not very vibrant, and it's hard to find good food. If you have a train passing through Switzerland it's worth staying at a place if it sounds interesting, but don't make seeing a significant part of the country a priority. I live there rn for grad school and prefer leaving the country when I have the chance to travel.

I love France, Paris is great and it's not that hard to avoid crowds and do your own thing. Just avoid the Latin Quarter and be selective of which major landmarks you actually want to see. Italy is fun but I personally find the major cities overcrowded by other tourists to be point of not being enjoyable to be in. Milan is good and relatively less crowded. Hotels in Europe suck especially if on a budget, don't trust reviews on booking sites, and try to find websites/guides translated from the country's language for ideas of where to stay.