1. The American political system is corrupt as fuck. _That_ is the problem in regulatory capture situations. You're trying to come up with a _workaround_ instead of fixing the core problem.
2. Anti-trust law works when it is applied hard. The EU has had plenty of successful cases where corporate behavior was effectively changed. But the organisations enforcing these matters are absurdly underfunded by decades of corpo-friendly right-wing governments throughout the Western world. Said differently: we haven't really _tried_ to do anti-trust well. Having said that, I am in favor of more structural changes like making corporate tax progressive, i.e. with multiple tax brackets.
3. Providing transparency is great, but the mistake in thinking is that people, even with full information _can_ realistically make different choices. On a geopolitical scale countries buy oil and LNG from heinous regimes because they have nowhere else to go. It is naive and wishful thinking that consumers will somehow force producers into behaving if only they had full information.
4. Counterpoints for nationalization: Your adversary _buys_ the companies that run your essential services, like utilities. Woops, should have nationalized or very, very, very heavily regulated them. Or: the industry is fundamentally unprofitable or profits more when society is doing badly. The US has a very, very wealthy healthcare and defense industry. Those fuckers are laughing all the way to the bank in times of war, prolonged and chronic disease, etc. The opioid crisis was/is a product of capitalism.
Nationalization doesn't mean "Soviet-style". There are many, many purely publicly funded organisations that work fantastically each and every day.
The key thing to realize is that the main strength of capitalism is in speeding up evolution. It _can_ do that, but we don't _need_ it in a lot of markets and 'late-stage' it favors stabilization and hegemony of a dominant 'species'. Again, it needs to be heavily regulated, so as to apply it precisely rather than seeing it as a blanket solution.