AFAIK it doesn't make a difference. As long as you have a Linux distro installed, the threats to privacy comes from close-sourced hardware (things like Intel ME). So it doesn't make much difference even for Linux friendly brands like Purism or System76. That's why Purism are making that phone which is more freedom respecting in terms of hardware.
I don't have any experience with the tablet side of things. But in general it is a good idea to look at the individual hardware components and see how well-sipported they are in Linux. The last thing you want is your new laptop's WiFi chip not working well with Linux.