Not sure when I first read that the PT2 would be constructed to allow for expansion for, among other options, the capacity to install celular (LTE) data modules - but it was definitely something talked about as "in the plan." I was disappointed when I casually inquired about it when I was finally actually ordering my unit, and whoever was returning email at the time stated that no, there was no LTE. I went ahead with my order anyways, because I wasn't sure if that person really understood the question, or knew tne right answer. So I want to post this here publicly to see if any other forumers had any experience upgrading to LTE, or whether it's even possible. My cell carrier offers a special unlimited data tablet rate of $15/mo which is why it interests me so much.
I don't know if you can add LTE or 5G or so. Reportedly it's not even advised to open the PT2 unless you really have to because you can damage the display connection.
That aside, my guess is that the bigger obstacle would be drivers for the LTE modem.
On the Pinephone it works okish after many years.
Even if you manage to shoehorn the modem into the case somehow it most likely would not come with linux drivers.
That said, my personal experience is that you almost always have wifi nearby for your tablet and if not I use a hotspot from my phone. Saves one SIM card.
I used to buy iPads with 3/4G but gave up on that. Your mileage may, of course, vary.
You could also remove the pogo pins for the keyboard and use that usb connection to power an eg25-g dongle mounted in the case. You would need to print a plastic back with more depth to accomodate it and add antennas for primary, secondary, and GPS if you want it. Your keyboard would be no longer usable of course.
Yeah, I would hate missing my integrated tactile keyboard (although it doesn't work right, anyways.