How common are laptops that don't work well with linux these days? With graphics you're golden: either it's AMD (uncommon) and it has working FOSS drivers out of the box, or it's Nvidia where you have working FOSS drivers sufficient for work needs, and proprietary drivers sufficient for whatever gaming you could possibly be doing on linux. With wifi, you're almost always golden these days. Most laptops seem to have intel or atheros chips, but even the traditionally hellish broadcom cards don't provide much of an issue from what I understand. If anything else in a laptop could cause you any real showstopping trouble I'd be very surprised.

Note also that both of these potential hangups are something you can easily access beforehand. Every site I've used lets you pick your wifi chip from one of a few choices and will at least tell you what the GPU is.