HUAWEI E8372 works great with all MX and Meraki APs, Just make sure you disable it's onboard WIFI and leave most settings at default.
Once plugged, Meraki will recognise the stick as a the cellular modem and it will act as a cellular backup when the default WAN loose connectivity.
Another brand that should work with Meraki is ZTE. Sadly, USB stick are disappearing from retail and most portable LTE modems nowadays are MiFI. Integrated LTE modems from most brands even Cisco often lack complete LTE band support.
Im very interested in this...At work, we use Verison for our USP LTE failover but for home, I'm not interested in a contract for home use...
I purchased the below one, its unlocked so it should work with ATT/StraightTalk, although I used a T-Mobile sim in it. I have attached to laptop, desktop, MX64, and MX67, no issues found. Usually gets better speeds than your phone in the same area.