Not sure about companies doing trips, but can help in terms of the type of riding as last year I did a 4 day trip from Geneva to Chamonix and this year I’m planning on doing a 18 day trip from Geneva to Nice roughly following GR5/TMB. We do carry all our own kit though (8-10kg each, including camping gear but not food) which does make a difference.
The riding can be pretty tough, but unless you are targeting long distance in a short time you shouldn’t have too many issues as it’s normally only short sections which are unrideable so can be walked. For reference we’ll be targeting about 1200-1500m climbing a day (30-50km a day), from looking at the route I know a decent amount of hike a bike can be expected, especially in the northern french alps, but these targets allow for this.