Scrambler
Well-known
SLR's are not "pocketable".
Get over it.
If you want TTL viewing, with a convential mirror reflex system, then the 1/2 frame Olympus Pen F with a 38mm f2.8 pancake lens will be the thinnest. The 38mm pancake is rare and breathingtakingly expensive, if you can even find one. If you can't afford the Zuiko 40mm f2 for OM then you won't like the price on the 38mm f2.8.
Quite honestly your requirments are at cross purposes.
There's one for auction today in South Australia (see other thread re auction) expected range 50-100 AUD!?!