Alertly

Alertly is an Android application by Daniel Saynov, licensed under Apache-2.0, aimed at cutting down how many notifications actually reach your attention. The stated goal is that only notifications counted as important get through, with the rest kept out of the way. This puts it in the category of notification filters rather than notification managers that simply group or postpone everything.

The listing states the goal rather than the method, so the criteria used to judge importance, and how much of that you can configure, are not described here. Anyone deciding whether it fits their situation will want to check that directly, since a filter is only as useful as the rules behind it.

Reading incoming notifications on Android requires notification listener access, a permission granted by hand in system settings, so setup involves more than installing the app. Android is the only platform listed, and there is no companion component elsewhere mentioned in these facts.