Everything you ever wanted to know about iOS security (and a few things you didn't know you wanted to know): https://www.apple.com/business/docs/iOS_Security_Guide.pdf

You don't have to leave the phone untouched for 48 hours. Even if you touch it you still need the passcode every 48 hours. TouchID only works for 48 hours past the last passcode login.

Not quite, the passcode is needed 48 hours past the last unlock but the clock restarts with every login or unlock including TouchID unlocks.

Just as a point of reference, Android has a feature by which you can register locations at which a PIN is not required. I've registered my home (which is not super secure, since GPS resolution means it works anywhere in my apartment building), and I have to input the PIN every morning because the interval resets every 4 hours.

Where is that feature?

It's called Smart Lock: https://support.google.com/nexus/answer/6093922?hl=en

basch what happens is, at a minimum, the iPhone requires your PIN or passcode every 48 hours to unlock. In between, you can use your finger as many times as you want. So the 48 hour timer should fire as soon as immediately after someone gets posession of your phone, but no more than 48 hours afterward.

that is not true, I dont type my pin in every 2 days.

from what I read, the device has to be left in a locked state for 48h.