I... don't think that's the case here.

In the specifications they state:

CPU separate from Baseband

My reading is that modem is connected to the CPU via USB. The only other project I know of that was looking at doing such a thing were the OpenMoko guys (GTA04 with an OMAP3xxx, I think? My memory is fuzzy on this).

AFIAK, there are no 3G/4G modems with an open source baseband. So the traditional route for libre/privacy conscious people has been to isolate the baseband from the application processor via USB. Normal phones have the baseband and SoC integrated on the same SoC and connected via a high speed serial bus.

On further reading, it's going to be an i.MX6 (because i.MX8 is not available yet and you don't typically use unreleased SoCs for your libre hardware) which is pretty inefficient by modern ARM SoC standards.

So this is essentially a small tablet running Linux with an integrated cellular modem.