I did a thing - unlock and enable legacy WWAN card on X1 Carbon 7G
https://github.com/fiboromcom/l850gl-fcc-unlock-linux
https://github.com/fiboromcom/l850gl-enable-linux
Having purchased a 7th Gen X1 Carbon from eBay a little while ago I noticed that the WWAN card worked perfectly under Windows, but was not visible under Fedora.
I decided to fix that.
This is the result of an extended effort to investigate, diagnose, research and deliver a comprehensive solution to the problem.
The first removes the FCC lock from the WWAN firmware to allow it to become visible to the system to begin with.
The second reassigns the device from PCI to USB and enables with a GSM profile to allow mobile data on the system.
There is also a service to allow boot-persistence so there is no need to manually execute every time the system is restarted.
I should advise this is a VERY narrowly scoped project - I only cared about getting mobile data working for MY system, and that is what it does - but I hope this can be a jumping off point for anyone else struggling with legacy modems on Linux, I hope this can be helpful to any and all.
Feedback gratefully accepted.