Sure. There are two ways to stream music directly from Apple Music to the WiiM Pro. With both of these methods, the music is not streaming from your iOS or MacOS device (you can test this by turning them off). My assumption is that the WiiM Pro device is streaming the music directly from Apple's own cloud services.
Here are the two methods:
1) From the Home app. Tap on the WiiM Pro speaker, and the speaker controls will initially come up (play/prev track/next track). However after a few seconds a selection of playlists from your Apple Music library should appear. It's a bit buggy - they sometimes appear and sometimes don't, or will appear and then disappear. But if they do show up, you can tap a playlist and it will start playing directly from the WiiM Pro device.
2) From the iOS or MacOS Music app. Tap on the AirPlay icon and tap 'Control Other Speakers & TVs'. Select the WiiM Pro device, and you'll be returned to the main Apple Music navigation, but you're now selecting music to play directly on the WiiM Pro device. This is not the same as selecting the WiiM Pro as an AirPlay destination for your phone. This user interface is not at all intuitive or obvious, but it works. You can then return to controlling music on your phone by following the same steps and selecting your phone as the device to control.
Apple is *so close* to having this nailed. They just need to make either/both of the options above a little more reliable and intuitive.