It can be done sometimes. If it is too far gone you might get some shine but not what it used to be. You absolutely need a good dual orbital polisher with the right pads. McGuire's makes a liquid restorer to start with and then go from there with compounds and finally protective wax.
Lightly sanding with 800 grit wet sand paper and water, followed but a rigorous buffing then a good sealant. This works just like a polishing compound with light grit but not as hard to do. You can't polish a turd...you need to dig into the dried out stuff and remove it. Covering it with "Shinola" won't work.
2018 THOR Chateau 35SF
Two Labs, Bugsie & Blondie