It’s a much too niche feature to be covered by one of the Youtubers like BoBeats (or even be covered in tutorial video at all).
IMHO it’s better to look around here on the forum in the “A4 category” threads.
A quite recent example from @sezare56 using a guitar signal as oscillator source:
There is nothing to be worried about. Just because it is not hyped into nirvana doesn’t mean anything. The A4 is one of the most versatile analog synths around.
Not directly related to the ext audio stuff, but I would suggest to check out the jam tutorial sessions from Gary Hayes using the A4: