FX File Explorer, seconded.

If you’re anywhere near PDX,

Free Geek

If the OP had a mechanism to opt-in to aggregated comments, rather than individual community comments, there could be an identifying notice that the comments of that post were being “hosted” in whichever community on whichever instance and were governed by their rules. Essentially, commenters would be guests in that forum and be expected to comport themselves accordingly. I don’t think it needs to be complicated for mod teams.

Consolidation is one of the things the fediverse tries to mitigate. I see your point, but federated services need some amount of redundancy and autonomy for the whole thing to work.

Not sure if this is the right solution for me, but really appreciate the in-depth post and compelling info. thank you!