Sorry for this shameless self promotion but I think that it could interest you.
I made these desktop expression controllers. Think expression pedals for hands, so analog, passive. I got this idea with the introduction of the control inputs on the last Elektron Analog machines, Analog Four mkII, Analog Rytm mkII and Analog Heat (both versions). I call them Sidekicks and the first one is a crossfader (I might be inspired by the Octatrack ).
And you can get them here : https://sidekicks.fr
Check it out