@hadon @jwildeboer @tante I would say, autonomy, as the word part "auto" suggests, can apply to people and institutions on their own. You can have autonomy from X.
Sovereignty includes the word "reign". You can not reign without an object, you can have sovereignty over X.
As such, the two words are completely different in the way they describe a power struggle. Focus on autonomy and you describe a situation where you want to be free from something (e.g. Big Tech, or US tech, or whatever). Focus on sovereignty and you (and not someone else) should have power over something, typically via property, law, infrastructure involved.
I think both can still be used from a right-wing perspective of (EU) nationalism, but autonomy is more open to anarchist anti-capitalist principles.