I've got two scenarios in mind:
- I'm writing some software for a RaspberryPi (in my case, it's a Pi4) and I want to test that software on a "box fresh" Pi.
- I want to give my RaspberryPi away to a stranger.
Let's say that I reformat or replace the Pi's SD card before doing either of the above.
With respect to scenario (1): will my Pi now be indistiguishable from a brand new one of the same model?
With respect to scenario (2): supposing that, for the sake of argument, the stranger in question had bad intentions, would he be able to access any data that I might have generated on my old Pi?