Which Smart TRV / Radiator Valve with Home Assistant?

That depends on the hardware.
The TRVs I had could be set to different temperatures and that meant the valve position was set differently

Yes, my two Eurotronic Spirit TRVs are doing that, too. They use the difference between target temperature and current temperature to infer a suitable valve position.
However, from the perspective of HA this behaves like a black box and I would appreciate if HA showed more awareness and exposed this information in the UI for instance.

I don’t know for sure, but I believe HA displays all the data it gets.
More likely this data is something the manufacturer does not want to expose.