I'm interested in trying out kubernetes on insider build announced today but wondering if secrets are supported, if not then I will not invest time into this whole thing.
Here is bug which was closed since it was noted that only next version of Windows will be able to do that. Docker swarm secrets working fine with current version.
K8 secrets support for Windows isn't in the current K8 builds. Docker did add secrets support for Swarm mode, though that also works on LTSC WS2016 hosts.