[jorams]

Sourcehut supports Mercurial, if the email workflow is your cup of tea. There's also Heptapod, which I believe is a fork of GitLab with added Mercurial support. I'm not aware of any Tangled or Radicle-like initiatives supporting it though.

[BrenBarn]

Yeah the email workflow is not my cup of tea. :-) Heptapod seems promising in some ways, but from what I saw it's entirely based on topics (not branches or bookmarks) which is also a peculiar workflow. Plus it doesn't have anything comparable to Github in terms of providing free hosting; in theory you can get free hosting for an open source project but you have to apply. At one point around when they launched, Heptapod said something like "we don't want to be a place for people to host their random side projects", but that's exactly what I'm looking for. I was pretty happy with Bitbucket before they dropped Mercurial support.