You can get laptops that have 5G radios that you can use for data with Linux.

As I understand it, there's no support for voice/SMSes at the radio level, but in theory, if you were willing to tolerate it and your cell service provider offers support, you could do WiFi calling.

Could also get service from a random other VoIP provider, use that over the data connection.

Probably not as battery-efficient, requires more of the stack to be awake to be listening for incoming calls.

I think that a larger downside is that Android software is designed for a touch screen and low power usage and low data usage across the board, and GNU/Linux software generally isn't.

We can say that for any kind of drivers needed to run a mobile phone.\ Manufacturers of components are less and less providing any documentation, just throw a binary blob and say "put it in your Android build".

They didn't say Linux phone though, it could still be android with a custom ROM.

Eh, Pinephone and Librem 5 made it work, but there's still a fair amount of software limitations here, and I didn't think Framework should be a software company. But the radios themselves probably aren't the blocker you make them out to be.