Well thanks to the help and pointers here I was able to navigate the truly atrocious documentation for flatpaks and was able to create a bundle. I need a few brave souls to test:
https://hobbes1069.fedorapeople.org/chirp-20200430.flatpak
I put the version in the name, so be careful, if I update it it, you could install more than one version. I still have yet to learn how you update flatpak packages.
I went through and did a "cleanup" of a lot of files we don't actually need. The original version was ~140MB...
It should be practical to get it listed on flathub. The archives are called "daily" but really it's whenever something significant has been committed and the date is the version.
Let me know if it works fine or needs some fixes.
Thanks, Richard KF5OIM