If a piece only conditionally doesn't participate in Ravage, and that condition changes mid-Ravage, does the piece participate for the rest of the Ravage Action?

If a piece only conditionally doesn't participate in Ravage, and that condition changes mid-Ravage, does the piece participate for the rest of the Ravage Action?

No. If a piece isn't participating in Ravage, it sits out the whole Ravage Action.
This most commonly arises for Wandering Voice Keens Delirium. If its Incarna is preventing Dahan from participating in Ravage in a land with Strife, that continues to be true even once Strife is removed to prevent Invader Damage there (or the Incarna is destroyed) – the Dahan don't get to switch back to participating for the counterattack portion of the Ravage. (If Dahan arrive in the middle of the Ravage due to a Blight Card, those new arrivals might be able to participate though.)