alt Hacker News> simulating a USB client device ... requires specialized hardware that is also very expensive
Pretty much any off-the-shelf SBC can present itself as a USB HID device like a keyboard. You can buy a very capable rp2040-based board for <$5.
What part of this equation requires expensive hardware?
The part where I want wired ethernet to that SBC, not some funky proprietary wireless chip as in ESP32. I almost found a solution, but I've been unable to get my picoprobe to properly flash and reset the board for some reason, so I haven't been able to use it for development. I'll have to troubleshoot that again sometime if I enter another bout of caring.