I have used Light Manager on stock Android where it worked fine.
However, it does not work under LineageOS 18 and I don't really like some of the default colours of LED notification (my custom colours are coming from my N900 setup).
Recently, I have found a surprise.
There is an option under Settings / Applications and notifications / Notifications / Special / Notification light (sorry, these names are not exact names) where there are some related settings.
At upper-right corner, there is an "Add" button, where an Application can be selected.
The selected application will b