A big feature like this will be at most 20-30% done when you open a PR, because the rest of the work is in collaboration to suit upstream which will as always require notable changes and rewrites.

Spending manweeks to manmonths on new upstream work that won't see any practical use until half to a whole year later, after getting legal to work things out, is a significant investment in new development.

This has nothing to do with suppliers or partners. They are not dumb enough to measure a product roadmap in number of random PRs, but will look at first party software and hardware roadmap.