I keep seeing the HSDeviceTile.xaml under some of my HomeSeer devices (together with an HSDevice type).

What is this for? What is the location of this tile (don’t see it in templates)?
Thank you!

It’s the default Tile template for some HomeSeer devices. Those XAML files are in the Templates folder for new projects. It’s possible your project was created before these were implemented. You can copy them from a new project into yours or use the “Synchronize Templates” command to automatically add them into your project. If you aren’t using the DeviceBrowser controls or the default Group pages, then you don’t really need those files. It’s OK for those devices to reference files that don’t exist in the project if you aren’t using Tiles.