You can have a primary network and guest network. As far as I can tell, you can’t have more than that.

You can set DNS manually.

Here is a link to a pretty comprehensive user guide that explains all the settings. Maybe I missed something about the SSIDs. https://static.inseego.com/us/download/mifixpro-userguide-tmobile.pdf

I recently got their hotspot and its been good. I got the MIFI X PRO 5G and have no complaints. I can’t speak to the privacy of it, but it uses a T-Mobile sim card. Do you have any questions in particular?