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I've used GPIO on a Raspberry Pi Zero W to talk with DS18B20 temperature sensors, along with an SDR attached with USB tuning in radio traffic and decoding AX.25 packets in software.

I've also used GPIO on a Raspberry PI Zero W to build a Stratum 1 NTP server with nearly spooky accuracy with the PPS line.

Both things worked very well. They were compact, performant, used an inconsequential amount of power, and were very inexpensive.

And both things were very easy for me to implement, largely due to the tremendous amount of software available in the Linux-ey ecosystem.

If I were trying to bodge an MCU into performing these tasks without involving Linux, I'd probably have never gotten either of them done.