Millennial Gardener and others pushing the Christmas tree lights and a decent quality frost cloth are spot on - it helps tremendously and really opens your options as long as you implement them in the 20-25 range. Haven’t tried the black pickle barrel trick yet. I actually killed my Browns Select by thinking it didn’t need protection until 20. It was in a bit too exposed of a location and I should have let it mature and lignify another year.
Ochard stuff is very much a lesson in Fail then Improve, and citrus hardiness tests def apply. My main point is that citrus conditioned to handle the 30s and upper 20s wil have so many fewer indoor problems (like mites) when you do have to wheel or carry it into a safer location.