is there a jj hosting service?

GitHub.

Jujutsu has changed how I work with git. Switching tasks is just "jj edit <change>" or "JJ new <change>". The only thing it can't do properly is git worktrees (it doesn't replicate the .git dir to the worktrees, breaking tooling that relies on git) but there is a (old) issue relating to it. Not sure on the priority, though.

Anyway, YMMV, but I love it.

I know of one: https://lubeno.dev

https://tangled.org/ supports many jj features, but they seem to only offer public repos.

We are working on something https://lubeno.dev

Looks like still a bit early for me, but if you add an RSS feed to your blog, I would at least be reminded to check it out again later :)

We use GitHub at my work. And I think I’m the only one using JJ.

Any service that hosts git?

Isn't jj git compatible so you can just use github?

Yes.