I highly doubt there was this much backlash, but was there any smaller protests that broke out within the respective countries?
/u/Abrytan is flaired for this:
/u/commiespaceinvader has answered (with /u/gingeryid) Are there examples of riots in Nazi concentration camps during the Holocaust? Were any of them successful? and Question! Why was there no revolution during the Holocaust?
I think commiespaceinvader has also written about backlash to the T4 euthanasia program somewhere, can't find it now.