So Officially giving up now.... here's where I got to should someone else come across this...
1) Armbian_21.02.3_Rockpro64_focal_current_5.10.21.img.xz : No monitor at all on USBC, and no HDMI-1 Res over 1920x1080
2) Armbian_21.05.1_Rockpro64_buster_legacy_4.4.213_xfce_desktop.img.xz : Gives mat res of Monitor 2440x1440, USBC Crazy blocks all over the place.
3) Armbian_21.02.2_Pinebook-pro_focal_current_5.10.16_xfce_desktop.img.xz : Amazingly USBC works up max screen res, sadly HDMI-1 not working at all. Zero joy doing a manual config for the higher res screen.
Looks like the new Panfrost work is very promising, which I could help but 23 years away from UNIX/LINUX development I'm way out of the game.
I shall wait a few months, If I can help with testing on the RockPro64 let me know.
Best
Rich