Until we can get the global surveillance apparatus dismantled, the size of the company doesn't matter. Small companies are easily bullied, large companies gain favors from cooperating and are also bullied via the threat of anti-trust.

I don't think breaking them up solves anything.

EDIT: A better but even more unlikely idea than nationalization would be internationalization, i.e. placing global companies under the control of international committees. I'm not holding my breath at this point though and the global dominance of the US means that unless Russia, Iran, and China are given prominent positions of control it's essentially meaningless.

Yet another idea is to force them to provide freely accessible API and possibility to extract all data in a free format.

This helps somewhat from a competition perspective, but the overhead of downloading and uploading potentially GB or TB of data (messages, photos, videos, etc) is not something users are accustomed to and is a significant barrier.

While it can make switching costs somewhat lower (does uploading your posts from another platform always make sense in a new context with new people?), it doesn't do anything about the network effect.

> overhead of downloading and uploading potentially GB or TB of data (messages, photos, videos, etc) is not something users are accustomed to

Users don't have to do it. See Nitter (for Twitter) and teddit.net (for Reddit).

Break them up and regulate the collection and sharing of personal information. Invalidate the freemium model by finding ways to make it more expensive to retain personal data.

The public is one entity- and will aggregate elsewhere, repeating the process. Humans aggregate, to expect a change in human nature is - a flawed approach.