Well, I've already had a decent amount of fanart with Errant, so I've managed to tick that box (but I'm always happy to get more!), so I think in terms of "stuff I'd like to see other people do in reaction to my comic", it'd be fun to see fanfic, or especially cosplay! I'd love to be invited to speak about my comic at some sort of big comics event on a panel, like MCM or something.
Anything beyond that though, like an animated adaptation, feels like a big stretch for a comic with my size of following, so I prefer to focus more on milestones I can achieve myself, like getting the books funded and printed (first one done!) and having cool merch like stickers, shirts etc. I have toyed with the idea of making a dub (it'd make sense since I dub comics as a hobby already... It's just hard work to organise), and I'd love to commission a music album some time.