Hi,
If you want to use a Nextion screen, that is probably what you should be investigating first.
But if you have not coded Arduino and or C++, you would best be to get a Mega or UNO and start some of the tutorials online to get used to the environment.
Timing an actuator is probably not the best way to calculate inclination, as the actuator speed will be dependent on load.
Some form of angular feedback from the putting green would be more reliable.
Tom... 