Fair enough then! I guess in that case maybe Lemmy with federation disabled is your best bet? I know you mentioned not doing this in your original post, but since if you were to use a standard message board software, it’s unlikely to have federation implemented (at least, I don’t know of any that work with ActivityPub) so you wouldn’t be losing anything more than with the other approach.
You could even go with lemmyBB which is Lemmy, with a standard forums interface.
utopify_org