Don´t shoot the messenger, but you are obviously asking questions here only to answer them yourself, also your "youtube and internet searches" are clearly focused on finding answers that you want to hear. If you use this audio science forum only to talk to yourself and confirm what you already believe, perhaps it is a waste of time for you and the others who are trying to advice you.
Dolby Atmos is metadata based matrix system, and the positions and movements of the sound sources and effects are coded in those metadata, but what you hear in your existing setup in your room is just mere interpretation of those data, done by the decoder/preamp/receiver, which is trying to reconstruct the spatial effects through your more or less optimal speaker configuration.
The more you will respect Dolby Atmos recommended numbers, positions, angles and distances of speakers, the higher is your chance to actually enjoy the Atmos recordings, which were mixed on proper setups.
I would strongly advice you against any type of upfiring "Atmos enabled" speakers, they are worthless in my opinion.
I would also not waste time with your idea of "just adding pair of front heights". It simply doesn´t work like that.
If you currently have 5.2 configuration, and you really want Atmos, position the 5 channels and install 4 ceiling overhead speakers following this recommended config, so you would have 5.2.4. It is almost always possible, where is a will, there is a way. Or just do whatever you like, but don´t call it Dolby Atmos
Learn how to set up Dolby Atmos 5.1.4 overhead speakers for an immersive Dolby Atmos experience. Get professional tips and guidance for optimal speaker placement.
www.dolby.com