Must admit I’ve not read the complete thread.
How about looking here?
ROCK 4C+ with Ubuntu 24.04 and ROS 2 Jazzy Jalisco
I suppose the relevant part:
In this case Rpi5b
Armbian_community_25.2.0-trunk.439_Rpi5b_bookworm_current_6.6.74_minimal.img.xz