He has a very dangerous mix of common sense and outrageous nonsense and no filter.
He is no politician, but he has changed US economics from "lets run the world", to US first, is pulling up the drawbridge that has allowed the world's problems to be managed by the US. I remains to be seen if that works.
I can see that supporting US industry and agriculture is a potentially valid tactic, given that the UK destroyed its coal & steel by allowing subsidised cheap imports, destroyed its fishing and dairy, by allowing the EU to set quotas that disadvantaged us.
Immigration policy is a sledgehammer though, given the amount of unused derelict towns and available land, but they do have a vast problem with illegal immigration, which disadvantages the legals, and introduces a vast number of children outside of the school and health systems; it also drives down wage levels.