Yes, I would like to get something like that. MODBUS is awfully insecure and I would prefer to run a firewall on the edge to restrict what/who can connect - (ie nothing
Have looked at some of the small openwrt based routers with LTE modem. As we also add a modem or other radios to get out of mining pits. But these devices all seem to be too small (memory/cpu) to run docker and the edge agent. Our agent on the other had runs fine in 128MB systems.
The PI isn’t the perfect fit, but reliably available, and consistent OS has been the main thing.
My ideal device would have 2 ethernet ports and an optional LTE modem (not USB based - had too many problems in the past not being able to reset them with out power cycling). Something like a Balena Fin https://www.balena.io/fin/ and just add the USB ethernet. it supports a Mini PCI express port so could add the LTE interface using that or an Ethernet. (I don’t need both at the same time).
Our requirements change each time we deploy. Custom built network, different modbus devices. Some with no MODBUS, etc… so each job is quite bespoke.