I think the answer is no, so this is probably a firmware suggestion. I can think of great applications for having your playing hands control more than they currently can by targeting velocity. Samples make a determination to trigger or not based on key range and velocity range. The suggestion to somehow limit the key range as a destination was suggested before a while back by someone dealing with wanting scenes to change the key ranges. Although that may work as well for the types of things I'd like to do - also velocity would work. If I could target the velocity offset (or scale) - then I could offset the offset with a control and make some elements trigger based on a controller (such as aftertouch). I know aftertouch and velocity presents a chicken/egg issue. The first note you strike with aftertouch is going to sound because aftertouch evaluation happens after the attack has already been triggered. I wouldn't mind tricks to enable, as a choice, delaying the evaluation of the velocity until after aftertouch is evaluated (maybe use the keyon-on delay of "1" - but this is secondary (lower priority to me).
I know XA can be used - but allowing velocity control (scaling) with offsets from control destinations would open up even more articulation choices.
What almost works is using key on delay (since it can be assigned as a destination). But there is no "infinite" setting - so notes still pop out when holding chords. The chicken/egg behavior happens on the first note - which is expected. If I set the initial key-on delay to be something higher than I think it would take to generate the offset with aftertouch - it'd be "nice" if the offset would apply retroactively since the key-on is delayed. It'd be nice to have the parameter open to offsets while in the key-on delay loop. This would allow perhaps tuning a delay that is playable during non-aftertouch playing (normal playing) and still able to evaluate aftertouch before the key-on event happens.
The end result would be 'something different happens when I dig in to the keyboard vs. not digging in". The vibes example where the mallet "mutes"/"muffles" the sound bar is one use. Setting up a sax performance where "digging in" will perhaps invoke the growl (instead of straight velocity) or maybe "digging in" will do something different like play key popping noises (the sound of closing pads on a sax which makes an approximate sound of that note - some players use these sounds in compositions/performances), or "digging in" triggers something else.
The difference between velocity gestures is that you can hold a note down (dug in) so aftertouch is still invoked and lightly play other notes - so you can get more dynamic range out of this potentially and without having to have a hand tied to the assignable switches for XA control.