It seems that today we can achieve similar functionality in fundamentally different ways (WSL, WSL2/virtualisation, Cygwin, etc.) What in your opinion is today's closest solution to colinux? and why we don't see such clever solutions today?
WSL2 is analogue to coLinux and WSL1 is analogue to Cygwin. WSL2 is definitely what you want in place of coLinux. However, both have merit in what they can achieve depending on the circumstances. There is long thread on Github about the switch between the two, with many people asking to maintain both.
