Open source it anyway. Things don't need to be perfect to be useful. The spirit of OSS has a lot of iteration, anyway. :)

This is a bad take man, "when its done" will never come having read through your comments on this you seem to really be going for some perfection in your hobby and until thats released won't release, but the issue is that rarely if ever happens, and instead of getting insights on your code and the community and yourself actually improving the landscape it's basically just a fancy exe, that no one will use actually because theres no where for it to go except in your head.

What most people do is they trademark the name, that way even though someone might fork, they have to use a different name.

Something else you can do is use (A)GPL3. This means you automatically grant patent licenses, and anyone building on your work also has to release their source. You can then separately sell proprietary licenses without any of these restrictions.