

This is not a driver. The README itself says:
Piper is merely a graphical frontend to the ratbagd DBus daemon
ratbagd itself, BTW, is also not a driver.
The unofficial open source license is called logiops, and according to the Debian site most of its builds are also under 2MB (and the two builds that aren’t are only slightly bigger)
There is also RatSlap, which I can’t find information on how big it is (and I’m not going to bother installing it just to find out)
Why wouldn’t they be? It’s not like they’re getting royalties from these journals…