I can’t comment on the EDK2 port for RK3588 platforms but I really recommend using U-Boot instead. With the RK3588 platform, we are at a point where we can dd U-Boot on an SD card (only takes ~8MB of space), boot a NixOS ISO (24.05 and later) and install NixOS on an NVMe drive like one does on an Intel/AMD computer.
Only caveat being that HDMI out works only on Linux v6.13 and later so if you prefer not to use a serial console, you need an ISO with Linux v6.13 and later.