Without a full blown email gateway to GitHub repo, this limits participation in the project too much - and GitHub doesn't provide such a gateway (although using GitHub Actions it might be in principle possible to implement it, mapping issues and PRs to separate mailing lists, etc...:-))
I might sound like a broken record, but getting a GitHub account does not need anything except a (working) email address.
For people who for some reason cannot get such an address, we can make an exception, on an individual basis (we are not in business of providing free email access, you know) and provide such persons with @
sagemath.org emails - email server runs on Unix VM, accessible via ssh and hosted in EU. (this machine is relieved now from sending trac notifications:-)).
Dima