Any idea what is the intended purpose? I mean, assuming good faith (which is not granted but plausible) how would this help them to build their distro.

I think it shows they didn't learn how to do it yet. Western companies had the same problem at first, now some of them know how to upstream a change. Huawei will learn to be a good citizen - they have to.

The issues mostly link to repositories that were created more than a year ago. So I think what happened is that they already forked the repo and made changes on top of it to get it to work on HarmonyOS, but there was no bandwidth for ongoing maintenance. Someone finally realized that this is unsustainable and demanded that the changes get upstreamed, but the people charged with implementing this directive don't know how you upstream changes. Hence this hamfisted attempt.

Most hits aren't even PRs, just issues requesting the repo maintainer to support HarmonyOS.