Comment by Twirrim

Firecracker, s2n, chalice, jsii.

On top of that AWS has done a lot of contributions upstream, particularly around the linux kernel, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin..., (particularly the virtualisation stacks involved), some around OpenJDK at what looks like an increasing pace, and the like.

To be clear: not an AWS employee.