Did the last remaining Neanderthals go the same was as mega fauna?
That’s an interesting idea, but by the time this alleged impact happened, the Neandertals had vanished into the hybrid that became early Europeans.
The conventional view is that the original paper on this was invalid:
https://en.wikipedia.org/wiki/Chiemgau_impact_hypothesis
> This claim has been refuted by geological research and the finding of a soil horizon of undisturbed peat and sedimentation since the end of the last glaciation period.[1][2] The lake is in fact one of many kettles under the foothills of the Bavarian alps.
My view is, they found evidence of impact, but obviously they are way off on the dating — the impact(s) happened prior to glaciation.