I currently have beryl AX router and I am trying to add cellular functionality to it through the USB 3.0 port. I looked at USB dongles and there are many 4G LTE dongles that I can buy and plug into the beryl and start using it.
However, I have also found this 5G card (with sim card slots) Amazon link
You’ll want to check the dongle has some sort of Linux support. These GL devices run OpenWrt Linux (21.02, soon to be 22.0x) ‘under the hood’. It’ll give you a better fighting chance getting it to work.
GL does not seem to actively publish a list of such supported hardware but I don’t use such dongles so there’s insight I’m sure I’m missing.