I am shopping for a new phone and it seems that my beloved notification LED has fallen out of favor, so I am willing to settle with Always on Display (AoD) as a second best.
I have been reading some and I understand that AoD is linked to AMOLED screens because in those you can "turn on" individual pixels, making it an energy draw small enough for it to be reasonable.
Now, I am browsing through GsmArena and I find that for AMOLED phones, some of them are qualified as having the AoD characteristic yet others do not show it.
Is it just because of some AMOLED phones being shipped without having the software option to use that feature (meaning that it could be added through third party software) or there are some hardware/firmware specs that make AoD unusable (either because it does not work or uses too much energy) if they are not present?
In short, I would like to know if I could add an AoD app to any AMOLED phone without expecting to suffer significant problems.