URP deferred rendering, Compatibility questions for mobile.

Hi all,

Since Unity moved 2021 to LTS I got a little interested in trying deferred rendering. Just wondering about compatibility on mobile though.
The docs are saying - Minimum Shader Model: Shader Model 4.5. and no OpenGL. Is that going to cut out a lot of devices?
Also will it fallback to forward rendering if the device isn't compatible?

Thanks!
Pete