Cover most of the smart watches out there

Hi folks, this may be a silly question, but I'm new developing for wearable devices, and Wikipedia says that there is Smart Watches with Android Wear 2.0 OS and Smart Watches with Android OS by itself.
https://en.wikipedia.org/wiki/Smartwatch#Operating_systems
So my question is, after Google released Android Wear OS there is no more Android OS Smart Watches on the market? only Smart Watches with Android Wear OS? should i worry about Smart Watches running Android OS nowadyas? because I'm developing an APP and I'm trying to cover most of the Android Smart Watches out there, so i thought in using Android Wear 2.0 SDK and Tizen SDK for Samsung Smart Watches, but now i don't know if i should worry about Smart Watches running Android OS, should I? if that's the case what would be the SDK for it? thank you very much for your help guys :)
Oh and for IOS, watch OS and Tizen OS will cover most of the smart watches for Iphones out there? thanks