Does it support eSIM? For backup internet, eSIM is good for avoiding monthly subscription, by paying per GB when needed.

I have a mobile 4g router from them and it supports physical esim. I even managed to get their suggested card for cheap. They have some support in their firmware to set it up, so you can do that fully on the router.

I have read that people managed to get an eSIM installed on it, but I think there are also physical eSIM options. See https://www.gl-inet.com/solutions/esim/

Edit: The SIMPoYo eSIM Physical Card (see https://www.gl-inet.com/campaign/simpoyo-cards/ ) seems really cool, may even be nice for a phone.