There is a lot of vague information such as "Android supports RTL since 4.1.1", from which I abduce that Android natively supports (some) Arabic, Hebrew, Persian and Urdu characters. Likewise some question on Stack Overflow such as What glyphs or character sets are included in Roboto fonts?, which is not definitely answered.
There are many scripts which are obscure by Silicon Valley standard but used by millions of people, such as Syriac or Amharic. I have noticed that new versions of Android display Syriac (since Oreo?), and further back (JellyBean?) support Amharic.
But I find it very difficult to just find a plain list of supported alphabets per Android version. Is it different per manufacturer, or does Google require every Android distribution to support at least a certain character set?
If I download an app with Amharic translations targeting API versions > JellyBean (for instance) should the developer include a font in the APK to be sure that I won't see tofus?