So I wonder whether FriendlyELEC based their 6.1 branch on mainline Linux
It doesn’t seem like it’s mainline it also uses Rockchip weird partition table so I couldn’t build a booting image with mainline image builder efforts.
At least Friendlyelec provides clean debian images now so making them DietPi is a breeze.
Then again for DietPi either going full mainline (with 6.6 LTS coming up) would probably be the very best way to go (but don’t forget mainline U-Boot then too). But to have full (confirmed) working support Friendlyelec’s 6.1 branch might be the smarter option