If you often use Spotify with Volumio, the following could interested you :
I have tested that : https://github.com/xemle/spop-web. I can be used next to the base volumio interface ( change the port to 3000) to access it.
It’s a little bit long to be installed, but it is build on a similar base than Volumio2 will be :
There is no volume control.
By waiting Volumio2