No port forwarding ever set up on my system! It’s bound to my interface and lockdown mode is enabled, all leeching and seeding is tunnelled fully.
Edit: as far as I’m aware, not being able to port forward only limits who you can seed to. Meaning you can only seed to those who do have port forwarding.
Expandable storage does not compromise waterresistance. If a phone with a Sim card slot can be IP68 rated, then a phone with a combo sim/SD card slot can as well.