So, no. None of your examples are equivalent to OOXML. The implementations were first opened up and then standardized.

OOXML was the other way around: Microsoft had a standard and tried to enshrine into a standard and force others to waste time and resources to be compatible.

Only if you ignore what was standardised in PDF form and only later made available on existing implementations.

That is why I explicitly made references to specific versions as turning points, as I expected the usual FOSS advocacy replies.