They're not adding ai to Firefox, at least that's not what the memo said, the memo said they were refocusing on Firefox (firing people who worked on their metaverse thing for example), and doing so on the side.
They specifically stated that Firefox mobile is a big focus moving fowards
to be fair, most people aren't using physical keyboards with their phones, this mostly applies to tablets (which are much less popular) and android tv (where firefox isn't even officially supported anymore)
anyway, even without that issue, the android version of firefox is kinda janky and regularly gets stuck while loading websites
bt keyboards can be absolutelly critical for some users with disabilities. most of the developing world can't afford to own several devices like a computer and a phone.