With Elvis - he’s a tad older and there were 3 very distinctive “eras” - Elvis as a pop act, the ‘68 Comeback special and Old and bloated Elvis doing Vegas shows.
Doing a movie on a single person and with all the focus on that person - it’s possible. Making 4 separate movies on the Fab 4 is just harder.
It would be like trying to make a movie about the Stones - pretty damn hard to do. I mean everyone above say 40 or so knows who Mick Jagger is - most would recognize Keith Richard’s - but a lot of people for example have no clue who Brian Jones was or his connection. The Stones when they came to America were very different than the Beatles who everyone thought they would be - kinda like they should just imitate the Beatles and be another pop act and not an English blues band.
If you tried to do a Stones movie - you’d have a very similar issue..it’s a hard transition from London, to coming to the States and going to Chess records - to surviving Beatlemania and retaining their own identity and then losing Brian to then jumping to Altamonte on to country honk/Graham Parsons before coming back in the later 70s as an arena band once again following the collapse of punk/disco before becoming the band that would never die.