I still use an unsupported 2018 Asus ZenFone Max (M1) ZB555KL X00PD with a broken screen. I’d like to change the screen.
Measures of the device: 156 x 77.5 x 10.6 mm (6.14 x 3.05 x 0.42 in).
Now, I don’t know if these are standard measurements for a certain set of smartphones (the ones that can be held and used with just one hand) or if any company can choose what size it uses for their devices, making finding a screen that fits incredibly more difficult.
The other question is, how difficult would it be to do it myself?
Putting in a generic screen with similar measurements is generally almost impossible. Looks like replacement screens for that particular phone are still available on Aliexpress though, so you could use one of those.