Would also like to cast my vote for ability to append additional tracks or whole albums to play queue. This is a feature I use daily on my other streamer, and would put WiiM in serious competition with the well known streaming hardware manufacturers.
Would be the most wanted combination for me. And quite sure for many others.
The Sonos UI AND HighRes. And with something like the Port or the Connect as bridge to existing stereo. The 24 /48 option in Sonos with Qobuz could be a first step in the right direction. Today we use Sonos for multiroom and easy listening. And the higher end options for dedicated music listening. But an budget item like the WiiM with an UI like Sonos would be great for many with a smaller budget.