An index of laptops that can run Linux would be a good thing. There may actually be something like that out there for all I know.
Dell has a specific model that supports Linux called Dell XPS 13 "Developer Edition".
As I recall, Dell has offerred Linux preinstalled off and on over the years. Not that long ago, I checked out of curiosity, and it appeared they had more than one model with a LInux option.
Lenovo I'm not sure about. Have read Linux runs well generally on them.
I'd heard not that long ago that Lenovo was planning on offering some models with Linux.
People have used Lenovos (particularly ThinkPads). But the brand is not 100% guaranteed--one writer has used some cheaper Lenovo, and reported minor problems with some distros.
ONE BIG PROBLEM...stuff does have a way of changing. (Stating the obvious, I know...) As I've mentioned, I think Dell has had on/off availablity of Linux systems. HP was once thought to be a "safe" buy--but I've heard of at least one situation where a modern HP just didn't work with Linux.
And let us not forget that distros can come and go and change.
The idea of buying a laptop that doesn't have Linux support direct from the manufacturer seems painful.
If things don't go well, it could be painful/frustrating/expensive mistake/etc!
I've never had a laptop, apart from some old PowerBooks that were obsolete long before I got them. Until recently, there was the thought in my mind that as much as I appreciate Linux that if I were going to get a modern laptop there would be a strong argument in favor of a MacBook, which--evne if I did nothing that benefitted from macOS, would at least be easy to buy! Plus...Apple does some things very well with laptops (track pads are generally praised, long battery life, etc).