

Yep, the M is for mb, that’s for RAM in this case.
As for levels… That’s not really that black and white, IMO, there’s no “best” platform, it’s always “it depends”. I think you’re fine with a pi, certainly for a while, and especially at the price point. Plenty of folks running fedi instances and Matrix off of 'em.
The only thing that comes close and has good software support would be a second hand small form factor office PCs, like HP mini PCs or the Lenovo ThinkCentre. Might buy you some expandability down the road, but it’s slightly bigger, uses a bit more energy, choices. It depends.
I don’t think “they should”, but if you’re willing / able to at least make a decent description of what it would entail, how it would work, and how it would benefit users, and possibly contribute in some other way, it might happen!
(It’ll take more than a sentence and a half from the sidelines, I think)