I was an early adopter of the STM32WL. I haven't been involved in Haystack for over a year, now, and (for the most part) I haven't worked on DASH7 for longer than that. My advice to you is to combine BLE + LoRaWAN; it gets you most of the functionality of DASH7, and these stacks are very mature and well supported. ST will happily sell you a WB + WL solution, and support it :) Or you can use something like a Dialog BLE chip + STM32WL if you're trying to make it as cheap as possible.
The LPGSM module does use the WL, but it is not intended to run DASH7. This module is intended to run a different networking stack entirely, although the hardware is certainly capable of running OpenTag if you were determined to make a DASH7 solution.
