Comment by rr808

I have a Pi Zero W that is a spooky-good GPS-backed NTP server. It relies on GPIO for getting tightly-accurate PPS pulses from the GPS module (which a USB-connected Arduino won't help me with -- the timing would be much sloppier).

I have also used a different Pi Zero W with an SDR dingle to decode APRS weather data, while also using GPIO to read a local DS18B20 temperature sensor and to switch a solid-state relay.

I could have done this last thing with any random Linux-ey PC plus an Arduino, but then I'd have two problems. (It would have also cost me rather substantially more money: I bought these Zero Ws very, very cheaply from Microcenter.)

I don't think you understand how GPIO is used on a Raspbery Pi. You can flip GPIOs in a BASH script, or set events on them in Python. GPIOs are first-class citizens in Rpi land, which is what makes it so convenient: you get GPIOs + Linux, seamlessly.

I have a Pi4 hooked up to a motion detector, a camera, a solenoid and some SCRs for a floodlight. A python script waits for an event interrupt from the motion detector on a GPIO. Then it turns on the lights and opens a door via GPIO, and starts recording in another thread (via a pipe to gstreamer). When the motion times out, it pushes the video to an private S3 bucket (using my own handshake for a token so that it can't be spammed).

(I used to have some GPIOs connected to motorized cat toys so that I could trigger them remotely while watching an realtime stream, but that throttled the above camera which was more important.)

... It is also a BLE gateway that monitors 4 temperature sensors, and also pushes that data up to the cloud with another python script.

... and it also is an MQTT gateway for a few NXP WiFi devices scattered around the yard, and their data ... you guessed it... is pushed up to the cloud (they control sprinklers because BLE doesn't have the range). I can log into my personal website and turn sprinklers on from anywhere my phone works.

Sure I could do the WiFi and BLE with a PC, but why waste the energy and space when I can use a tiny Pi that is already doing a bunch of other things?

I just keep adding things to it because I have my own cloud system (HomeAssistant is a big fat bloated joke).

Having a good BLE sensitivity and WiFi chip on a tiny linux board that runs dozens of python processes listening to GPIOs, and running Gstreamer would be too much of a hassle with a PC and far beyond an arduino.