As far as I know the VTthermo app, Virtual thermostats and also actual thermostats are all more or less based on “hysteresis” control. Please proof me wrong
In other words the heating is on when the set temperature is higher than the measured and turned off when the temperature reaches the set temp+hysteresis. Actual thermostats have also some on/off timed switching (They say its PWM, but made with relay/contactor) when the off limit is close, lets say 1C away, so that the temperature doesn’t overshoot the set temperature.
It would be great to have PID controlled thermostat, virtual or real one. That way you could finetune the heating so that the overheating and underheating could be minimized. Of course the tuning is still quite long process to do, because you have to adapt to winter/summer, moist/dry and so on.
Of course you could do the PID with Better Logic calculation or Homey Script if you have the time an skills to make it, but it would be nice to have for example additional app for it to make it easier to use.