Developing PIO programs for the Raspberry Pico RP2040 chip is really hard, since -- in contrast to the ARM cores -- access to the PIO's inner state is very limited, and debugging output and tracing almost impossible.
Therefore, in early 2021, I implemented an emulator for the RP2040 PIO, and a set of tools (for the command line as well as GUI based) and a very simple scripting language for program control and debugging output. The tool set thus supports developing PIO programs by running on the emulator, step by step, if desired, and inspecting as well as logging the PIO's inner state and all GPIO output. Source code is available on GitHub (https://github.com/soundpaint/rp2040pio), and detailed documentation on Read the Docs (https://rp2040pio-docs.readthedocs.io/en/latest/).