I don't mind the events/contests/competitions idea but I feel like the number of active users here (and I do mean active, not just up/downvoting submissions) is a bit low for that. Unless the idea is to use those events to make people engage more with the community. Plus there's the already mentioned issue of reward restrictions.
If you do decide to go through with a contest, the first one could be about potential banner replacements. Kill two birds with one stone and all that.
I'm not sure how flairs work on Lemmy/Mbin etc. so I'm curious what you have in mind - some pre-made ones (in-universe manufacturers, factions) or an ability to put your own text (within reason obviously)?
While I do have the time, spend a lot of time on the platform and I'm still trying to keep up with the project, I'm not sure I'm active enough in this community to offer my services as a mod. I'd be willing to help if there's need and no other candidates but that depends on your expectations and needs.
Either way, congrats on stepping up and good luck!