Hi @jrnijboer,
Envoy is in the process of being ported to Windows. An initial alphia was announced back in September (see Announcing Alpha Support for Envoy on Windows). There was a recent presentation at ServiceMeshCon which discussed the latest status of Envoy on Windows, and the roadmap to a GA release.
There’s some work needed in Consul to support running Envoy sidecars on Windows, but that should hopefully be a relatively small set of changes.
Aside from Envoy, there are currently no other options for an L7 proxy that supports Windows, and is integrated with Consul. However, it is possible to build one using the steps outlined in Consul’s Connect Custom Proxy Integration docs if you need a solution sooner.