@The Real Grunfink You don't have to apoligize, I know stuff like this aren't easy. But I guess, reading your answer about transfering follower, that I did not explain myself clearly. Sorry, I should have been more precise.
I wasn't talking about migrating a Pleroma account to another account on a previously existing snac instance, but to replace Pleroma by snac on my own server while keeping the same domain/account/etc. Thus, there should be no need to ask people to follow me elsewhere, as, seen from the rest of the Fediverse, I'd stay at the same place.
I guess the difference between identifiers could indeed be a problem, but it may be possible to add a redirection from the old /notice/ to the new format, to at least keep the links working (won't be way more problematic than my current situation, I guess).
I hope it's a bit more understandable now, and once again, no need for apologies, answers would never disappointing me, especially since I know I'm asking for something really uncommon.
I'm afraid what I said applies the same even if both services share the same host and domain.