Depends a lot what you’re looking for in a seedbox. If you want to race then a lot of the options given are great. Personally I want storage capacity above most things and grabbed a dedicated server from Hetzner auctions. Today you’d be looking at 40TB gross storage for €60 a month. Been a long time since I’ve looked at setup options, swizzin was hot stuff then to give more of a “seedbox experience”

Isn’t it typically just kernel sources that would need to be released under GPL? A custom kernel is typically a few steps later in bringing up a custom rom for a device. The existing build is probably enough to try and get twrp running if you can get the bootloader unlocked.

Edit: All the same, very noble. Best of luck getting the sources, and making something useful of them.