There are two I know of.

The Barge Concepts VFB-X is a blend loop/feedback loop pedal which offers expression-pedal-based control in addition to static knob settings. The fun part is, you can control either the blend loop or the feedback loop by an expression pedal.

There’s also the Morley FX Blender, which is a blend loop pedal enclosed in a Morley Wah housing. Basically, the expression pedal is a permanent part of the pedal.

Honestly, these are both a challenge to work with properly in practice, because of changes in gain as you sweep from fully dry to fully wet. You will experience a dip in volume when moving towards 50/50, and an increase in volume when moving away from that point. While I have seen blend knobs on some effect pedals which have been carefully adjusted at various points to maintain a consistent level of volume across the board (without additional knobs), I have yet to see this in a blend loop pedal, much less, one with expression-pedal-based control.