It's not harder than it looks.
The most difficult thing is choosing the compound to use so I'll help you with that:
https://www.cleanyourcar.co.uk/sonax-ex-04-06-polish
The Halfords DA is actually very good. The key thing is it has an 8mm orbit so really works the compund and means you don't need to spend hours on one panel.
I built my own hifi speakers, sanded, filled primed, painted and laqured (all automotive car materials) then colour sanded and polished with the Sonax and the Halfords DA. The attached image is actually MDF!
Also images of my car before and after.