Growing up I had more flight deck visits than I can remember, getting the jump seat for take off and landing wasn’t unusual. Some airlines had procedures and a minimum age for pax to visit the cockpit.
I remember one visit on the BAC 1-11 as a 12 year old, the transponder had the three different emergency codes written on it, squawk number and meaning next to it except that the last one had the meaning left blank. I got some very odd looks when I asked if that was the code for a hijack.
Newer generations will have to make do with DVDs.