Just had another idea.

As the grass gets crushed and pushed out of the way by the walking figure.

Set a ball in your scene.
let the ball follow the figures movement and let the grass collide against the ball.
(it will move out of the way as the ball passes throught he grass.)

Or use 2 balls, one for each leg.

You can set the ball(s) invisible in the render, so the ball(s) will push the grass out of the way as the figure passes in the sim, but the ball(s) will not be rendered.

You can morph the ball(s) into an egg shape for better results.
Or use inverted cone primitives to get the same effect.

(Parent them to the shins.)

Let the grown grass collide against that balls, or inverted cones.

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