Jump on you tube and check out Carl Paoli https://www.youtube.com/user/nakaathletics
He has a book called Freestyle, but a lot of his stuff is on You Tube as well.
Another place for Pistol Squat Progressions is found in Mike Fitch’s Body Weight Athlete program. https://www.globalbodyweighttraining.com/bwahome/
Pistol Squats aren’t essential for cycling performance, but they could help. Particularly if you don’t have access to barbells, kettlebells etc. Pistols generally allow you to demonstrate good mobility and stability / motor control.
There are many other options for body weight single leg strength training. Split Squats, Lunges, Shrimp Squats to name a few.