Simple question, how do you even play this game? And what are the struggles? Thumbs, index finger, both hands, one hand... The usual stuff

Most of you know I play with only 2 fingers ( right hand )! At first it was easy but now I continue like this because 1. I'm too lazy to change the way I play this game, that's somehow possible and 2. Not many people play like that and i think it could be cool to try. My biggest problems are drumrolls ( tho I'm really improving on them!!! ) and that my whole arm can hurt if the song is too hard.