Are Icaros Shell Extensions open source?

No

Icaros is, at this point in time, not open source, so this repository is for tracking issues, and downloading the latest releases of Icaros

github.com/Xanashi/Icaros/tree/87ff8d06#icaros-shell-extensions

Not at this point in time

github.com/Xanashi/Icaros/issues/40#issuecomment-1438366646