As a solo developer, wouldn't all these git repos be on your local machine as well?

What risk are you trying to avoid?

If gitlab or github is down and you have the repo locally, you don't have an issue.

If you've already handed off the repo to someone else, that's on them to store it and it'll likely be under their account.

I guess it's not clear from your intro what features you use 3rd party git hosting for other than backing up your repos.

Are you submitting pull requests to clients? Tracking issues? Other?