Explorer HAT Pro and an on/off button

I understand that an on/off button (or perhaps more accurately a shutdown/wake button) can be set up for the Raspberry pi by placing a button across pins 5 and 6 - see https://www.raspberrypi.org/forums/viewtopic.php?t=191145 - with some scripting to make sure shutdown is handled properly.

The pinout at https://pinout.xyz/ identifies pin 5 as BCM3 (SCL), and one of the 3.3v points is labelled ‘SCL’. Is this the same pin, and if so would putting a button between this and the GND pin on the 5v-safe side have the same effect?

Yes I have a 2 pin / wire cable plugged into Pin 5 and 6. I have a momentary contact normally open pushbutton switch on the end of the cable. When I press my button it momentary shorts the two contacts and grounds pin 5. I’m using it to make my Pi boot up. I haven’t done the or tried the config.tx edit. That Pi is running Motion Eye OS. I’d be interested to know what effect that has on i2c devices? It’s not going to physically damage anything but I’d think its going to mess up i2c signalling when you ground pin 5 SCL. Likely not a big deal as your shutting down anyway. Curious non the less.