+1 but only if you’re serious about diving down the home automation rabbit hole.
The approach that I’ve found to work well is that Home Assistant provides the real “brains” of my house, and almost all of my smart devices are connected there.
I then use an HA integration with HK to expose those devices to HK so it can act as a “voice front end” to HA.
Implementing your requirement of a “default ambient brightness” would be straightforward to do in HA. I use the word “straightforward” intentionally, as it assumes you’re comfortable with basic concepts of coding. There’s a Node-RED plugin for HA that provides a visual programming interface that may help you. (I’m an old school programmer, so am more comfortable with raw code.)
I haven’t tried this, yet, but to take advantage of the multi-admin feature of Matter, you do something like this: