I don’t know what role ssh-agent plays in this as I’ve never used it, but plain ssh keys have been working fine for the windows users at work for some time now.
It’s still miserable to debug the problems though, so you may want to try your luck by being an early adopter of
It is now possible to use an external
gitexecutable instead of the default libgit2 library for the downloads that happen via the Git protocol by setting the environment variableJULIA_PKG_USE_CLI_GIT=true.
from the Julia 1.7 NEWS.md. Julia 1.7 is presumably getting close to a beta release but for now you can try it out with a nightly build.