Problem is not user activity - it just needs PIN, TouchID or FaceID. Even if you logged to device via iPhone Mirroring it's still gonna reboot, get locked after 72 hours and for me personally it breaks iPhone Mirroring half of the time too.

One physical option to bypass it on iPhone SE is to actually physically activate PIN entry and then use Voice Control command to enter the pin since it works even before first unlock. Though this is basically compromises pin and device encryption. But it's cheap since there are plenty of $2 devices that can simulate touchscreen clicks.

I just want some easier option that works and not require agent 007 setup to just run a buld of my AI-generated crap via Xcode.

Issue is, you kinda have a agent 007, sort of setup with the advanced data protection thing. I think you need an appropriate solution.

But all I want is "Please dont reboot my phone! Very please!" setting in options.

I can understand Apple on this. They make phones for the general public not HN and many people are stupid enough never to run updates.

might have to resort to the homer j drinking bird to tap the screen (for reference https://youtu.be/R_rF4kcqLkI?t=174 )

No joke btw I already testing setup with auto clicker from AliExpress and Assistive Touch automation...