To add in the fancy slider you want so much, there needs to be a corresponding tunable in Wayland. MacOS does this with plists, it's not some radical or hated design pattern.
>>smolde+(OP)
If you think that is a "fancy slider" you lack perspective. It is a basic, expected feature that is supported by Windows and macOS for laptop users. And I'm pretty sure it used to work on Linux too, before Wayland.
>>twblal+k
It indeed used to be supported before Wayland. I don't develop Wayland though, and if I did then it would look very different from how it exists now.