For me, using Armbian, the device tree for Rock 4c+ has the &tsadc disabled.
I had to add an overlay to enable it, in order to get CPU/GPU (SoC) temperature.
I’m not sure why this and also mali-supply (GPU regulator) are disabled by radxa. Without mali-supply, the panfrost driver doesn’t seem to load, and GPU works very badly / not much at all.
Maybe there is a reason why these are left disabled, but I have ~25 of these 4C-plus in use as RDP thin clients using Wayland, and they seem to work pretty well to me, once everything is figured out and enabled etc.
The overlays I’m talking about are mentioned in the comments here: