Without any further configuration, might as well as add that to your edited paraphrased quote.

The op said it wasn’t working, I’m only agreeing with him that it doesn’t work as expected.

Your lengthy explanation of flatpak doesn’t seem to be postmarketos related.

My statement is true , that flatpak is arch agnostic but primarily supports x86.

I never said it didn’t or wouldn’t work; if you’re not seeing your apps it’s not because they don’t exist, they aren’t built for aarch64 and target x86

https://discourse.flathub.org/t/how-to-provide-binaries-for-both-aarch64-arm64-and-x86-64-regular-64-bit/3521

Flatpak while agnostic is currently only working as expected on x86_64

https://github.com/flatpak/flatpak/issues/5210

Postmarket uses Alpine for its base; if the package exists in the Alpine base repo you’re using then no issues.

https://liliputing.com/how-to-install-apps-in-postmarketos-with-phosh-shell/