HomePod no longer responds to Siri

I'm specifically hoping for some sort of remote control app for iOS.

The standard Music app can be put into a mode where it acts as a HomePod remote control: the user can queue individual tracks and playlists, and the HomePod will play them using its own connection to Apple Music and the iTunes Music Library.

It is a little tricky getting the Music app into that mode.

One way is to open the Control Center, then long-press or force-touch on the music control. This reveals separate control panels for your iOS device and any other controllable devices, including AppleTV and HomePod. Tapping the HomePod will open the Music app in HomePod-control mode.

Workflow on iOS allows you to perform web service calls and send commands over SSH. The Siri shortcuts functionality coming in iOS 12 appears to be based at least partially on Workflow’s technology (Apple aqui-hired the developers.)

As to whether all of Workflow’s functionality will appear in Siri Shortcuts at some point, I have no information either way.

Even if it does, it would be up to you to provide some sort of endpoint/plumbing on the Windows side to actually pull this off. You’d be fully on your own.