Nice post and repo!
After I've run into various hurdles with getting buildx to work on different systems, I've also written up a post on Building Multi-Architecture Docker Images With Buildx detailing a bit more what constraints need to be met in the Linux environment. Hope that helps others debug faster what it takes to get it to work for them.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.