I have experimented with this lever with what are very tight tires (Gator Skins) on a tubeless ready rim (Mavic Cosmics). I have very poor thumb strength due to constantly spraining them in football and basketball, so changing tires is hard and I have to use my palms. Which blister!
I found these worked, but not great. I practised using them, but still not sure if they are worth it. I prefer to use my hands, but if I can’t get the last part of the tire on, I would use my VAR levers while on the road. I do think it’s potentially a good product that needs some fine tuning . I will practice with them some more and I have a feeling that after more practice they will be useful. I like the compact size and the light weight. They do barely fit over my 25 mm tires and wouldn’t be suitable for wider tires.