

The other option here seems to be using uboot to boot your SD card: https://docs.u-boot.org/en/latest/usage/partitions.html
Since you know you can boot it via USB, you can just tell it to then boot from your SD Card instead of relying on the r4s to boot it. Docs say it’s possible to flash to the eMMC as well https://wiki.friendlyelec.com/wiki/index.php/NanoPi_R4S#eMMC_Boot
Look at the Framework Refurb store.