A well-functioning market has rules. Different rules might be appropriate depending on the market.

As an example, rules that prevent phone subscriber lock-in and makes it easy to switch provider, those constrain the possibilities of the providers, but at the same time they facilitate fierce competition over end-user prices - possibly creating a better market by creating a good playing field for the competition to play out.

Its good for the consumer because replacement parts can be sourced from many different places. Imagine if each big furniture shop had their own exclusive screw sizes And you have to repair the leg of your chair.

Some standards are definitely required; electrical safety for mains items, non-toxic paint, FCC style emissions control etc. A world of no product standards is basically worse than AliExpress. Or people's regular complaints about Amazon.

Well that's why these entities have a constitution, to define government's prerogative. So to answer your own question you need to read the EU constitution.

Well, that's a debate.

Do you need/want a centralized authority dictating requirements for quality, safety, and interoperability? When and how much?