Regarding Smyth and OOYH etc, we are comparing apples and oranges.
Smyth realiser uses HRTFs and works best when you use your own measurements made at the ear canal entrance (partialy blocked) for the speaker setup you are interested in. You then have to choose a very transparent headphone to play the PRIR back, Smyth also uses a headphone EQ to invert the headphone response you plan to use so that you don't get a double HRTF (playing back PRIR without EQ over a headphone will sound harsh especially near 3 -5k). But keep in mind you are comparing Mobius priced less than $400 to a full fledged desktop setup that costs upward of $2k in addition to a headphone setup you will need. Symth Realiser is great in convincingly replicating an existing setup, it is a different use case, it is not portable.
OOYH uses (to my knowledge) measurements based of Smyth Realiser (using Smyth's in ear microphones) but played back using a convolution engine on Mac or PC. These are not personalized so for critical music listening, you will have to add your own EQ both for your ears and for the headphone you choose, but does not do head-tracking and is not available for mobile platforms.
Mobius uses Nx algorithms for the surround processing for a convincing image (though not like a true floor standing speakers several feet away, but more like studio monitors), presets already account for the native response of Mobius drivers so you do not have a double HRTF effect.