The short version is that, no, you can't law yourself out of this (or pretty much anything. )
Firstly, laws have national jurisdiction. There are no "all the countries agreed to this" laws.
Secondly, the US can't actually pass any laws anyway. Congress is deadlocked. It can't even get around to killing daylight saving clock changes (which passed the senate with unanimous support.)
Plus any laws (or, more recently executive orders) just end up in court forever. And when passed may, or may not, be enforced (or enforceable. )
And that's before I point out that big tech buys (sorry, "lobbies") govt in the first place. Apple, Meta, Google would all pay to make this bill go away.
Lastly, everyone seems to forget that interoperability leads to spam. Email is open and completely flooded. SMS is open and basically unusable. Whatsapp grew their user base in part because the experience was spam free. So even if laws declaring openness were proposed they would be far from universally supported.
Why do you assume that the regulation that would actually get passed by the actual government would result in effective chat interchange between different protocols, and not just entrench some existing platform while making it technically illegal for another organization to try to compete with them?
> Either you provide message interchange with any other message system operating in a specific country or you can't advertise or sell anything in this country (also app stores must country wide ban).
Would this make it technically illegal for me to use F-Droid to install an open-source implementation of a novel chat protocol that doesn't support interchange with existing chat platforms yet? Does this make it possible for me to force existing chat platforms to be suddenly illegal by releasing a novel open-source chat protocol without coordinating it with those platforms?
> Would email look the same if it was left to be invented by the corporations?
Probably not, but email is a heavily-flawed protocol, so I'm not sure that's a good thing. Also, although email was invented in the 1970s, making it one of the oldest internet protocols still used, it's been extended over the years, and I'm sure at least some of those extensions were developed by various for-profit companies (perhaps ones which no longer exist).
Either you provide message interchange with any other message system operating in a specific country or you can't advertise or sell anything in this country (also app stores must country wide ban). Bootstrap by taking two largest chats and offering them provisional access to the market for few months. If they can provide interchange between them they can remain and others can follow. If not bigest one is out, let's say for two years and the third one (pre-ban) tries to establish interchange with the remaining of the two biggest.