I'm building a project that I'd like to eventually sell in small batches as a commercial product. The RPI Compute Module 4 I/O (CM4IO) has most of what I'd need, but one extra thing I need is the ability to connect a 3.5mm audio jack to use it with headphones or speakers. Adafruit has something, but I'm not too sure if it's compatible:
The product description there does say "works with any and all Raspberry Pi computers with a 2x20 connector", which covers all boards except the original 1B (= a 2x13 breakout).
The 40-pin headers are intended to be compatible across all models, and while I do not have a CM4 board, it looks to have one near the "Raspberry Pi HAT" label, so this should be fine.
This is confirmed in the brief description here: https://pi4j.com/1.3/pins/rpi-cm4.html