Randomized MAC addresses is a neat idea, it also helps bust through the time limits of free WiFi that only give you something like 30 minutes per day (because they use the MAC to identify if you've used up your 30 minutes).
The observed behavior on my Pixel is that it generates a new, random MAC whenever you connect to a new network. It reuses that MAC for that network going forward. It does not ever use the "real" MAC unless you specifically select that in the settings.
But practically when I do this in the UK I can leave any information I want including my neighbour’s name and then start Googling for “bomb design at home without getting caught”
