If there's some set of fully Linux-capable laptops out there, it's a small subset of the Windows-capable ones.
And it's not clear what the Linux ones are. Like, our dept ordered officially Linux-supported Thinkpads for whoever wanted them, and turns out they still have unsolved Bluetooth audio problems. Those people use wired headphones now.
This is true. Until people pay reliably for Linux hardware instead of Windows, that will always be the case, just as it is for Mac.
Just like Mac, though, the key is to buy from a vendor that ships hardware designed for Linux, with Linux preinstalled, and with support for Linux.
Unlike, Mac, though, Linux won't block you from installing it on Windows hardware, so it's not as obvious that you're on your own.