I have some small amount of experience with this, but based on the little I know, here's what I can say. First question is what is your goal? To get customers, or to create a community? Below is general advice but it's hard to say just talking about it in the abstract.

If you want a community, I would probably advise to just treat it as one more channel, have separate pages in Meta / X / Fediverse / Pinterest or whatever as separate communities, since in a lot of cases there won't be overlap between them. I wouldn't recommend abandoning your existing Meta or X pages to set up a Fediverse page instead, although making a contingency plan for the slow motion demise of Meta as a platform for the long term seems like a good idea.

If you want to drive sales, then for me Google Ads always worked better than buying advertising on Meta or X or etc anyway. Have you measured conversion numbers from Meta? They make it easy to spend money definitely, but I always found the ROI in terms of pure paid sales to be pretty bad from them.