Not all coatings have enough effect on the oxidized look of UV-damaged plastic. Most dressing restore the look better, but don’t offer the protection of a coating. Combining these 2 seems illogical and difficult, but it isn’t.
Wetsanding isn’t very difficult in the steps you need to take. It’s the technique that makes the different. When mastered, wetsanding can give very good results, but it is also very risk and should be done with great care.