Hi,
good news:
after mainline uboot was broken for r2pro/rk35xx in 2022.07+, a new patch series brings support back in 2023.04 (when merged to it but i think mergewindow is closed for this, else in my repo).
https://patchwork.ozlabs.org/project/uboot/cover/[email protected]/
edit: added changes to new 2023-04-bpi branch too and build uboot including a basic sd image with github actions. done this for r2 (mt7623 too) to have all binaries and sdcard image templates there now.
regards Frank