Ah , interesting - hadn’t seen them like that before – but the premise looks the same to what I was suggesting.
In the video on the product you can see them mucking with AT commands. OpenWRT seems to be using https://openwrt.org/docs/guide-user/network/wan/wwan/modemmanager so I think you’d just want to confirm the chips on those dongles have had success with ModemManager - and then be running ModemManager from your Pis.
https://www.amazon.ca/Dongle-EG25-G-M2M-optimized-Module-Global/dp/B096TQJR73/ref=sr_1_13
Ah , interesting - hadn’t seen them like that before – but the premise looks the same to what I was suggesting.
In the video on the product you can see them mucking with AT commands. OpenWRT seems to be using https://openwrt.org/docs/guide-user/network/wan/wwan/modemmanager so I think you’d just want to confirm the chips on those dongles have had success with ModemManager - and then be running ModemManager from your Pis.