Probably an unpopular opinion here, but these aren't technical issues. They're cultural. Bounties won't fix it. In the case of the file picker issue, there have literally been third party patches that the GNOME devs could have used.

I couldn't stand more than a couple days of following their gitlab discussions. Each issue goes through roughly the same process: someone suggests a feature or a fix for a thing, the GNOME devs either say "#WONTFIX you're holding it wrong" or get mired into an endless debate of the minutia of the _best_ way to implement the feature.

If you want to fix GNOME, you'll have to replace the entire leadership structure _and_ a good portion of the devs (and somehow get them to ignore the zero-utility clingers whose contributions consist of endless discussion posts but no code). As it is they act like they were hand-picked by Microsoft to make sure progress happens slowly (if at all).