So an American PPL (no IR) cannot fly "VFR" above an overcast layer?

Yes, but that is not VFR-on-Top.

To clarify, yes he can fly VFR above an overcast layer, but doing so is
not called "VFR on top", rather, it is called "VFR over the top".

Confusing terminology - think
"VFR =on= top, your (IFR) clearance is ON"
"VFR =over= the top, your (IFR) clearance is OVER"

Jose
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