Maybe it's just that I can't find it, but I only saw one forum that said that that for turning my game into an App for Android/iOS you convert the game to HTML + JavaScript with QuestJS, but the issue is that QuestJS doesn't support all of Quest features. I'd like to know what features it doesn't support?

Is there even a way to export right now to android/iOS that works?

QuestJS is what is used to port games to iOS and Android. Theres a lot of games which are marked on the site as apps:

http://textadventures.co.uk/games/tag/app

If you play a few of them you can probably glean what kinds of features of Quest work well in apps.

The way to go about it would be to download QuestJS from here: https://github.com/textadventures/quest-js

...and start working on a game, and running QuestJS on it as you work. There's no document of what is supported and what isn't. Work has started on Quest6, which is a javascript only implementation, and I believe QuestJS is not going to be further maintained.