SourceHut staff here. We don't have any requirement for "real legal" names or anything -- and in fact I find these requirements very harmful in general (glad we finally got rid of them in the kernel). I know multiple people collaborating on SourceHut with a pseudonym and this causes no issue at all. SourceHut does assume a stable email address but that's about it.
That's my own take -- for Drew's see https://drewdevault.com/2023/10/31/On-real-names.html