Debugging Ubiquiti's 5G Backup on AT&T

For a mobile 'mini homelab' project I'm working on, I wanted to use 5G Internet as a primary 'on-to-go' connection, but still have the ability to plug in another Internet connection when I put the mobile rack I'm building in a fixed location. I'll have more on that project soon, but I figured this project was a good way to check out Ubiquiti's solutions, especially considering many of their smaller gear fits nicely within the dimensions of a mini rack (the 3U DeskPi RackMate TT is pictured above).