can you inflate as a animation using the Pressure Constrain Stuffness Slider ?

also I tried using the Constrain Vellum Property as shown in the video below

is an expression the only way to animate a value ?
or am I missing something trying to keyframe the value slider ? is that logic not the Houdini way ?

you can directly animate Stiffness on Vellum Constraint Property DOP, no need to write the vexpression
you can also play with animating Rest Length Scale

Thanks Tamte Legendary