I often use picos because they're much more capable when it comes to interfacing with hardware.

You can do gpio, pwm etc from a linux pi but the hardware is worse at it and you'll be fighting against the system quite a bit. It's a lot of boring complexity to be allowed to do something simple; and the next update might break it.

If I need a linux system AND hardware interfacing, I'll usually use a regular pi + a pico for the hardware stuff and connect them via serial or something