I noticed while poking around my Stream 3's firmware that it's running a whole embedded Linux/Buildroot stack (kernel 5.10, U-Boot, BusyBox, BlueZ, etc.). Sent an email to HumanWare support requesting the GPL/LGPL source packages, and Mathieu Paquette, product manager for the Stream 3, happily turned around and sent over the link with zero hassle in a little over an hour. If anyone wants to dig into the packages under the hood, including HumanWare's .patch files:
https://humanware.s3.us-east-2.amazonaws.com/victor/GPL/legal-info-packages.zip
I said this when I got the evolve's NVDA source code, and will say it again. Massive props to HumanWare and its product managers, Mathieu in this case, for actually handling GPL compliance properly and quickly without making people jump through a million hoops. Love to see it!