The best replacement for volume pedal is expression pedal.

The best alternatives to volume pedal are rated as following:
★★★★★  expression pedal
★★★★  attenuator
★★★★  volume knob
★★★  wah
★  goodrich
★  ernie ball

Your alternative for volume pedal is not listed? Suggest!
Speaking about volume pedal, one probably shouldn't forget about lap steel.

Other search terms related to volume pedal and their ratings are:
★★★★★ lap steel
★ wah
You have in mind a companion for volume pedal and it is not yet here? Propose!



Google Trends

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volume pedal
expression pedal
attenuator