Sort of... but that could be due to a host of other factors besides which language is better: how good the core developer(s) are at community-building, how committed they themselves are to the project... hell, even the fact that one project used GitHub (which reduces the friction for developers who are already on GitHub to start working on the project), while the other one has its own GitLab might be relevant.
> https://www.redox-os.org/
Doesn't that sort of prove my point?
I dunno if you've tried both SerenityOS and Redox - I have, and SerenityOS is just more complete and usable as a daily driver than Redox[1].
Redox developed over 7 years has less functionality than SerenityOS developed over 4 years.
[1] They both have a long way to go before being completely usable as a daily driver, but Redox has a longer way to go than SerenityOS.