[kaspar030]

Technical differences aside:

RIOT is the only mentioned OS with a copyleft license (well, LGPLv2.1), trying to create a FOSS alternative in the embedded/IoT space.

With permissive licenses for embedded software, open source usually ends at the factory.

[pjmlp]

Yep, the anti-GPL crowd will miss the glory days of Linux, specially if Fuchsia really turns into Android Next.