The biggest issue I have using these with arrangers, is that all keytars are made to be played with the right hand.
If I'm going to play keys and sing, I want to control the accompaniment (LH chords and bass) just like I've been doing at home for years. I'm afraid if I try to relearn the chords to my favorite songs right-handed, I'm only going to confuse myself!

It seems to me that a keytar-like instrument could be made such that the keyboard controller and "neck" could be configured by the user for left- or right-handed play.

If not, I guess another mobile solution is this... :-D
https://sano.shop/en/products/detail/233864