The main thing that determines if a computer can be repaired is parts availability. Those three have great parts availability almost universally.
If you wanna run macOS you need a Mac. The t480 is a good recommendation for thinkpads, but don’t worry about ssds or ram yet, just get the one with the processor and display you want (it’s the midrange 8th gen ones). I don’t know the dell world enough to make a recommendation but someone will do so.
Use the gentoo and arch wikis to check what problems people have out of the box with whatever model you’re looking at.
People will say you need amd. This is either paranoid or based on recent events. Neither apply to you.
People will say to get a framework or some equivalent. They’re expensive and a moral/ethical statement. This doesn’t apply to you.