MiFi Hardware with ZT Support?

Hi Team - I’m interested in MiFi type devices (personal hotspots, battery powered providing WiFi clientside and 5G/4G upstream) and wondered if anyone had success with such and either using an OpenWRT version (with ZT support) or, indeed, compiling source for a specific MiFi product ?. Alternatively, if anyone has some good ODM contacts to look at, perhaps, having a specific unit built (with relatively large volumes, etc).
Thanks in advance,
Steve