It just works – “vanilla” Debian on Pi 3B/3B+.

Pete Batard, who has single-handedly upstreamed the original RaspberryPiPkg to TianoCore edk2-platforms, has an excellent blog post up for a while now, detailing how easy it is to install vanilla Debian on the Raspberry Pi 3B/3B+ with UEFI.

https://pete.akeo.ie/2019/07/installing-debian-arm64-on-raspberry-pi.html

And of course, the Raspberry Pi 4B UEFI is an evolution of the Raspberry Pi 3B/3B+ code.

The Pi 3B/3B+ is still a great platform to explore UEFI functionality, and it’s EBBR-compliant UEFI boot for Linux (that is, with device tree) is still way better than messing with config files. Plus you can do PXE and iSCSI. Isn’t that awesome? Or port Doom to it :-).