what will be if I use sudo rm -rf /?

[OstaptsovDanil]

I'm afraid to try it, but I assume that the iPhone will not allow iOS to be taken down

[carbon-starlight]

It seems like BusyBox's sudo implementation does not have the --no-preserve-root safeguard, so you will likely delete everything in the filesystem of your WM, but not iOS device (that's an emulation, remember?). It would be interesting to try this out though right after fresh installation, maybe I'll try that out on my old iPhone (after I'll fix it) where I didn't install and customize iSH yet to easily reinstall the app after.

[HVRyan]

It should not affect your phone at all; everything is contained within the emulation (unless you mount into Files).