For Twitter-alikes (Mastodon, Misskey, etc.) you probably want to be following hashtags instead of people, though that's not really what the UI will initially drive you towards. That'll let you follow topics and interests, with the option of also following people you find interesting from the hashtags you're following.

For video transcoding, eh, maybe, but that's a solved problem: the iGPU on a modern CPUs can do more video streams at basically zero power usage than I'd ever need.

For Frigate? Oh absolutely. That started out requiring a TPU (A Coral at like 2 TOPS) for anything resembling usable performance, and then built some GPU models. No reason you couldn't use a 50 TOPS NPU instead, other than software support.