Yeah, that's a good idea, 'them' would be a better choice than 'it' I think
Very much so.
'They' or 'them' is plural. There is only one pixie at a time.
You can't say 'a xxxxx pixie invites you to follow they' .
Actually, they and them are not just used in plural situations. They and them are also used when one chooses not to apply gender to themselves or others.
but you could put "one of the pixies invites you to follow them" or
A shy pixie invites you to follow
I like this idea, too. Instead of debating back and forth over which pronouns to use, you can use this wording and nix the entire pronoun altogether.