Google and Apple smartphones are incompatible when communicating via text messaging. You can't send more than one picture back and forth. You can't send video. You can't send texts without the text breaking up. Text messages being broken up is also an issue between phone carriers because their APIs are not the same for SMS. And as of 2020, you can't send texts to groups. Text messaging is a means of communicating but you are limited in that regard. Would this be against the First Amendment of the US Constitution?
The First Amendment says that the government cannot pass law restricting speech. It does not say that everyone is compelled to take actions that enable others to speak. The First Amendment would tend to work against your plan, because Congress generally can't pass a law to force people to "speak" in a certain way, and Congress cannot pass a law forcing you to provide your soapbox to your opponents. As an expressive matter, Google is expressing its right to "speak" in a particular manner, one that happens to not agree with how Apple talks (which is their right). However, the Commerce Clause of the Constitution is widely invoked as a means of compelling businesses to do something. If the government has a compelling interest in a certain end, Congress might pass a law that forces companies to do something. The political part, which you'd have to undertake, is persuading Congress that... the government has a compelling interest in [fill in the blank] w.r.t. phones, or computers, or what-have-you. Congress sometimes leaves such matters to the market, so that a competing company that unifies all communication could have a competitive advantage and could be more successful than a company that was more proprietary (although, at a certain point that advantage becomes a disadvantage and anti-trust actions take place). It's just a matter of persuading enough Congressmen to pass an appropriate law that does what you want done. By reference to the Commerce Clause, other considerations of constitutional rights can usually be finessed, although Google and Apple's First Amendment rights can't trivially be swept away by saying "effecting interstate commerce".
The US First amendment limits what the US Federal and State3 governments may do. They cannot, for example, forbid you from sending text messages, nor can they require you to send messages.
The First Amendment does not operate to control private people or companies. It does not require different companies to use compatible systems, just as it does not require a newspaper to print your letter or a website to accept your post.
It might be constitutional for Congress to pass a law regulating text messaging in such a way as to force interoperability. I think it would be unwise, as such a law would tend to lock in current tech and discourage innovation. In any case Congress is in no way required to pass such a law, and has not done so.
It would be plausible for the various service providers to come to an agreement on protocalls so that there would be greater interoperability. Or someone might develop software that translated from one format to another. Such an agreement would IMO be a good thing, but no law requires it.