support for darker app icon background

The left side of the image above shows how icons currently look in LineageOS even when the dark theme is enabled in the phone settings. At least when using the default launcher, Trebuchet (com.android.launcher3).
Right side is how I imagine that icons should look like with dark theme enabled.
Ideally, this change should take affect across whole system. So on home screen, in the app drawer and in all other parts of the UI where app icons get displayed.

My two questions for you:

1. Any ideas or suggestions for what options or workarounds could be used to achieve this right now?
   • Yes, launcher with support for custom icons could mitigate part of this issue.
   • Themed Icons affects just home screen and changes whole icons instead of just background.
2. What would be the development / contribution process for introducing this functionality into LineageOS by default?
   • LineageOS issue tracker prohibits submission of feature requests. Which part of the internet would then be most appropriate for discussion about how to make this happen?
   • Is this even within a scope of LineageOS? Should this feature be implemented within AOSP in order to get introduced into LOS?