This isn’t necessarily true. If you are using an identity provider, you can still perform a password reset on GitLab and set a password there, bypassing your 2FA on GitHub. You usually shouldnt rely on IdP 2FA unless the destination system enforces IdP signin every time. There is a group setting in GitLab that does that, but it will only apply for that group.

Check out https://arstechnica.com/gadgets/2021/08/point-to-point-wi-fi-bridging-between-buildings-the-cheap-and-easy-way/ which is a good article on how to do this