I was weighing the practicality of making a 3rd party module myself, so I’ve just looked into that device you linked, and it seems like the company that makes that also sells mPCIe cell modules (a “module” is apparently just a modem on a circut board with a SIM card holder) https://novotech.com/sma-male-to-n-female-fll195-1-foot.html. So basicially, It seems like you could just buy one of those, and as long as it has compatable drivers with your OS, you could replace your wifi chip with one of those. the only problem is that you wouldn’t have WiFi, but making a WiFi module would be easier. Also maybe it wouldn’t fit in the laptop’s mPCIE.
Maybe what would be a better idea is a generic thunderbolt to mPcie module? I don’t know, at this point maybe are you better off just getting a normal usb-a cellular module.
Also I’ve surmised 5G tech seems to be hard to get ahold of at the moment.