Hello Ropotrop,
I am new to the Openwrt. I am using 24.10.1 on the R5C NanoPi and have it succesfully running on internal eMMC (the SquashFS version). I used the following youtuber as guidance "The Workshop On The Hill" https://youtu.be/GsxuoSXb9A4?si=OJgbYKaj4QPYaI4i