Hi everyone, and thanks to @fmaurer for pointing me to this thread.
This device looks interesting (and cheap), however we are not dealing with a Qualcomm wireless SoC (IPQ) here, this is Snapdragon X65 (Codename Lemur, successor of the SDX55 alias SDX Prairie). I have a few devices with SDX55 already (D-Link DWR-2101 portable router and DWP-1010 outdoor CPE), but the next steps for these would probably be adding support in postmarketOS.
SDX55 is even in mainline, and there are some devices (5G modules) supported, but adding this new target to OpenWrt would probably be a lot of effort (though I hope to see it one day).
These routers are not even like Android phones without screen (which have an application processor that talks to the baseband processor), these things are just the baseband processor.
As seen in the log, they run QTI Linux, which even uses a preempt kernel since it has to take care of many real-time tasks in the modem, and load binary blobs into the modem hardware underneath etc..
So, it's definitely feasible to run a customized Linux on this thing (and learning postmarketOS has been on my list for years), but I'm not sure how much of the kernel patches requires by gluon would be adaptable to postmarketOS, or how simple it would be to support this new target in OpenWrt.
Some progress has been made with very old cellular Qualcomm MSM89xx chipsets (found in ~10 $ LTE dongles with 150MBit/s), there is a fork of OpenWrt that supports these https://github.com/HandsomeMod/HandsomeMod and quite some discussion is also happening here in the forum UF896 - Qualcomm MSM8916 LTE router ~384MiB RAM/2.4GiB flash, Android: OpenWrt?, so I hope one day we can also have SDX55 and SDX65 devices, but at the moment this is beyond my skill level 
//edit:
Since last year, I've been struggling with DWR-978, which is MT7622 + SDX55 conencted via MHI (both PCIE and USB), it kind of works sometimes but is annoying, e.g. some pins need to be pulled before performing reboot otherwise the modem won't come up... when it does not, triggering a pci rescan in the kernel would find it, but modemmanager would not see it etc...