Registrars don't usually care. Well, they started caring for the very first time with kiwifarms for some reason, but that's another story. The problem is hosting providers. But I don't think heyuri is so big that it can't reliably be self-hosted as is, is it? You could slap that shit on a raspberry pi and call it a day, even, so long as you can get a static IP or an IP resolution service.
You also don't have to worry about looking for another registrar yourself. If Epik does go out of business, they will transfer your domain to another registrar at their own expense. If you don't like THAT registrar then you can move afterward, but that's not usually a problem either.