If I understand correctly powering on a pie has nothing to do with code.
However powering off can be acheived through Python GPIO or just using dtoverlay=gpio-shutdown to /boot/config. txt on your Pi.
I still need python anyway for other GPIO pins.
config.txt
/boot/config. txt on your Pi
The system configuration parameters, which would traditionally be edited and stored using a BIOS, are stored instead in an optional text file named config.txt.
Add the line dtoverlay=gpio-shutdown to /boot/config. txt on your Pi
https://www.raspberrypi.com/documentation/computers/config_txt.html
dtoverlay
Device Tree overlays. Device Tree makes it possible to support many hardware configurations with a single kernel and without the need to explicitly load or blacklist kernel modules.
https://github.com/raspberrypi/firmware/blob/master/boot/overlays/README
Name: gpio-shutdown
Info: Initiates a shutdown when GPIO pin changes. The given GPIO pin
is configured as an input key that generates KEY_POWER events.
This event is handled by systemd-logind by initiating a
shutdown. Systemd versions older than 225 need an udev rule
enable listening to the input device:
ACTION!="REMOVE", SUBSYSTEM=="input", KERNEL=="event*", \
SUBSYSTEMS=="platform", DRIVERS=="gpio-keys", \
ATTRS{keys}=="116", TAG+="power-switch"
Alternatively this event can be handled also on systems without
systemd, just by traditional SysV init daemon. KEY_POWER event
(keycode 116) needs to be mapped to KeyboardSignal on console
and then kb::kbrequest inittab action which is triggered by
KeyboardSignal from console can be configured to issue system
shutdown. Steps for this configuration are:
Add following lines to the /etc/console-setup/remap.inc file:
# Key Power as special keypress
keycode 116 = KeyboardSignal
Then add following lines to /etc/inittab file:
# Action on special keypress (Key Power)
kb::kbrequest:/sbin/shutdown -t1 -a -h -P now
And finally reload configuration by calling following commands:
# dpkg-reconfigure console-setup
# service console-setup reload
# init q
This overlay only handles shutdown. After shutdown, the system
can be powered up again by driving GPIO3 low. The default
configuration uses GPIO3 with a pullup, so if you connect a
button between GPIO3 and GND (pin 5 and 6 on the 40-pin header),
you get a shutdown and power-up button. Please note that
Raspberry Pi 1 Model B rev 1 uses GPIO1 instead of GPIO3.
Load: dtoverlay=gpio-shutdown,<param>=<val>
Params: gpio_pin GPIO pin to trigger on (default 3)
For Raspberry Pi 1 Model B rev 1 set this
explicitly to value 1, e.g.:
dtoverlay=gpio-shutdown,gpio_pin=1
active_low When this is 1 (active low), a falling
edge generates a key down event and a
rising edge generates a key up event.
When this is 0 (active high), this is
reversed. The default is 1 (active low).
gpio_pull Desired pull-up/down state (off, down, up)
Default is "up".
Note that the default pin (GPIO3) has an
external pullup. Same applies for GPIO1
on Raspberry Pi 1 Model B rev 1.
debounce Specify the debounce interval in milliseconds
(default 100)