Tock OS has a nascent Thread implementation that can not only interact with other Thread devices but can also communicate with a Thread Border Router. To get an idea of what network-connected projects this makes possible, I do some network performance testing and discuss the results.
A while back (a few years ago, actually), I wrote a working audio DSP engine on the RP2040. I delve into the details of how it works and demonstrate a flanger effect I wrote for it.
Configuring the Pico's PIO state machines without using the SDK. The datasheet and associated documentation got me most of the way there, but I encountered a couple of obstacles with non-obvious solutions which I cover here.