Yes, I agree : I
want strong effects in the pedals for the best immersion feelings ! no cheap vibration
My approach will be to test my available "hacked" motors : RC plane motors, Wingman logitech FFB motors...
The H-bridge board I intend to use can handle 2 x 800 mA, I'll have to measure the current while running.
I'll use an electrical connecting block ("domino") to make an excentric mass

and the Wingman FFB logitech Joystick as a USB board

after analysis, there no motors dedicated to vibration inside : the force motors are used as well to shake (back/forth).
For bass shaker plugin, it's a good idea Yokoyoko : once you got an amp, it could be cheap to add Loud Speaker buttkicker on pedals... but I won't explore the subject now ! I'm overwhelmed (3DOF and pedal, and lurking to Mizoo Wheel ...)