You can put the repositories on pretty much any static hosting. I haven’t tried it, but I’m pretty sure that, with a bit of fiddling, you could even put them on a github pages site.

Both distros have good tooling for maintaining repositories, and I’d say it’s probably easier than getting your package into the official repos and keeping it updated there, especially on distros like Debian which favour stability over having the latest versions of packages.

No distribution system is going to be entirely friction free for the author, but I’ve not encountered any significant issues hosting deb or rpm repos.