It's cool to see such an impactful project choose sovereignty. I hope more projects follow their example.
If you're a backbone-of-the-internet project like FFmpeg is, living on GitHub seems horrible. You will be subjected to thousands of low quality pull requests and issues from people searching for typos to fix, adding a line of white space for a contrived reason, or similar nonsense changes. Just so they can put "FFmpeg contributor" on their CV (or whatever).
Thousands is quite the exaggeration when there are only 379 on ffmpeg github. If you look through them, its actually 5-10% if not less
So its nice the US has a competitor here