There have been some notable discussions here on this subject.

https://news.ycombinator.com/item?id=22076348

That's an excellent talk, thanks for sharing it.

And yes that USB gadget thing. I had to use it recently to turn a RPi Zero into a parallel -> USB converter. It's impossible to debug and sometimes makes you question your own sanity. Here's my script that does it: https://github.com/grishka/miscellaneous/blob/master/AVDecod...