Britain’s Black Arrow could, but it launched from a RAF base in Australia. Definitely not continental Europe, but part of Europe if you consider it from the Eurovision point of view.

A real shame Britain abandoned their own research.

> Have there been other rocket launches from continental Europe?

Continental Europe? yes. The Russian's Plesetsk Cosmodrome is well within the boundaries of the European continent.

Continental Europe outside of Russian influence? no.

From a sovereignty perspective, does a launch from continental Europe actually matter when Arianespace/CNES/ESA has been launching from France for decades?

Yes, but most of them in the early 1940s.

Orbital? Maybe not. Sub-orbital and ballistic? Absolutely.