I hosted GitLab Community Edition on-prem as a trial for a very small team, but switched to a Microsoft offering. Part of it was it being demanding, part of it was not. The point is you can host CE yourself and get an experience that’s very similar to their service, “for free,” where “free” translates to your hardware requirements and responsibility. I’d even say it’s worth it to go with GitLab, in that context, for the familiarity you can provide your team. “You’ll have to learn gitonator9000” turns into “you’ve used GitLab, right?”

Personal use? You could run it in a container and periodically backup your data. Is it proportionally more demanding than other things? Probably.

A method in an interface (or a function in a trait or equivalent) should be unequivocal, as it’s literally a contract.

I think there’s nuance in the private scope, especially in variable names, but I’d still expect the name to be fairly explanatory. Maybe not EnsureUserCreated(UserDto userData), but still EnsureCreated(UserDto user).