I don't think this is possible with a hotspot from
a cellular
connection.
You are behind a nat on cellular, which shares one public IP with many
and doesn't allow routable ports/protocols.
The only solution would be to get a public IP address from a home
connection or a vps, and setup a VPN to access it from remote.
I could be wrong, but that is my understanding at this point.
Not only that, but some VPSs do not allow loading the IPIP module, which
means that a full KVM virtualized private server is the only solution
short of setting up a VPS to announce a /24 via BGP.
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Kris Kirby, KE4AHR
Disinformation Architect, Systems Mangler, & Network Mismanager