How to access hosts behind AT&T hotspot

[plumpychunq]

Here is a request for the networking Gurus.
I have an Opnsense router whose connection to the internet is an unlimited AT&T hotspot. I would like to access some equipment (Nextcloud, cameras, etc.) behind the Opnsense, however; AT&T doesn’t give you a public IP unless you’re a business customer and pay $$$. Does anyone know of a way to be able to access a Nextcloud fileserver (or any host) that’s in this situation?
Perhaps some sort of “Jump Desktop” service?  Or a persistent reverse SSH tunnel…?  I’m just not sure.  Has anyone done this?
Thanks!!