When it comes to open source projects before you do any work go and look at the merge requests/PRs and look at who is getting them resolved and if lots of them are seemingly stuck. Some projects just don't take PRs from unknown people and they don't invite contributors onto their team, those projects with one maintainer and little community collaboration aren't worth writing code for.

There is a constraint still but a project like the Linux kernal has put a lot of layers of review and testing and merging between the source of truth and the underlying contributions. Having a number of leutenents that deal with subsections of the system that test merges and review the contributions is necessary for a project to grow.