This reminds me of a thought experiment I did once. What would happen, ignoring that it’s impossible to create such a thing under known physics, if you had a one-way portal: step through one side, immediately end up in the other, but going back is impossible. For visual purposes: unless it was transparent to light, the “enter” side would be pitch black, and the “exit” side would show a (possibly distorted) bright image that would be the overlap of the entry site and a mirror image of the exit site. (If it was transparent to light it would just be invisible.)
The portal would need to pull you through, otherwise anything pushed through would emerge as raw energy. Thing is, though, I’m not sure if there’s any safe speed for any living things to pass through it. There will be a buildup of blood, body fluids, and nerve signals on the exit side and nothing returning to the entry side. Too slow, and this buildup could be fatal. Too fast, and the G-forces could kill you, not to mention that you’d go flying across the exit area. Depending on exactly how it works and the energies involved, there’s the possibility that some forms of disruption (potentially including someone grabbing you too late to prevent you from entering) could split someone in two. Even if there’s a safe speed and no real risk of something going wrong, you’re going to lose consciousness regardless, and your breathing and heartbeat will stop as the hindbrain and spine passes through… though whether these are momentary, permanently until medically revived, or somewhere in between, is something that can only be guessed at, since brains and nervous systems are not at all designed to be forced through a one-way portal.
It’s not the same as what OP is suggesting is possible in their sci-fi fantasy (essentially, that reality is a simulation which can be hacked in a very limited and specific way), but since they’re seriously entertaining fantasy physics, I figured I might as well do it too.