Ish, it hasnt seen much development in recent times but seems there's still dev interest to continue development https://lemmy.blahaj.zone/post/13166332

Eternity has a data saver mode

No, that's a different protocol, the tearing patches, already merged, but i believe we're still waiting on some patches to the kernel to get them fully working(i think it was kernel 6.8 that had them), Nvidia's drivers also need to add support for it, they've given no timeline for that so far however

https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/65

That blogpost is considered to be somewhat flawed with its information, as explained here: https://tesk.page/2021/02/11/response-to-flatkill-org/

You can, infact there's outright a mesa git runtime one can add, i don't imagine too many systems roll so fast as to outpace it https://docs.flatpak.org/en/latest/available-runtimes.html