Google is already doing that since last year and the models where never leaked, so I don't think that would even be a problem.

https://cloud.google.com/blog/topics/hybrid-cloud/gemini-is-...

Are you also talking about personal projects? That wouldn't be enough for me for work either, but for personal use, my $20 Codex subscription is perfectly fine. Then again, as a new dad, I can maybe only work on personal projects for 1 hour in the evening if things go well, so for my current situation in life, it's enough.