@steveff Our Matter integration is just around the corner. For the Twist this is probably most relevant for lights, as no speakers I know yet support Matter.
What we also have in the pipeline for Twist is e.g. more configurable steps (4 -> 12) for Advanced Dimming/Scene Blender so that you can trigger an action (e.g. Alexa) with higher resolution and before as well as Hub SDK features for the Twist so that you can build custom integrations.
Spotify has an API (over cloud) that we could potentially use for controlling the volume, but we are not sure if the latency will be low enough to make this action have a good user experience. We also don't like that they don't provide any means to "push out" the volume status when it is changed so that the LEDs on the Twist could update accordingly (https://community.spotify.com/t5/Spotify-for-Developers/Access-to-websockets/td-p/4955299).