> if developers actually used a small set of common runtimes instead of picking from one of a gazillion slightly different rebuilds
All the runtimes on Flathub are built on top of the standard fd.o runtime, so the OSTree-level dedup should generally work for them.
> Unfortunately (and ironically) it's ill-suited for games, which need to have the latest GPU drivers available, which is antithetical to the whole idea of a stable, universal base system.
I believe there's an extension available for the latest Mesa builds, so you can opt for the bleeding edge and then just remove the extension if things break.
All the runtimes on Flathub are built on top of the standard fd.o runtime, so the OSTree-level dedup should generally work for them.
> Unfortunately (and ironically) it's ill-suited for games, which need to have the latest GPU drivers available, which is antithetical to the whole idea of a stable, universal base system.
I believe there's an extension available for the latest Mesa builds, so you can opt for the bleeding edge and then just remove the extension if things break.