The source code itself is just Git, so you can 'git clone' it anywhere. Add that host to your origin(s) and just push it as you always do. However, other data

The source code itself is just Git, so you can 'git clone' it anywhere. Add that host to your origin(s) and just push it as you always do. However, other data such as tickets, PR history, gists, etc. will be a lot harder to keep in sync with another service. GH allows exporting all the data, per GDPR, but importing it somewhere else will probably not be possible.