What about the right of citizens to install whatever software they want on their phones?

They never had that. e.g. Apple.

To be more specific, it would be Apple preventing you from doing it in this case.

If you had a phone that let you install software on it of your choosing then you could install whatever you want, regardless of who Apple isn't allowed to do business with. They made themselves a chokepoint, so now they're a chokepoint.

The internet interprets censorship as damage and routes around... no, your phone's only route is through the one corporation.

You're free to jailbreak your phone if you want to exercise that right. And Apple is free to deny you updates and service if you do that.

How so? Americans have the right to trade with foreign companies. Apple should have the right to trade with foreign companies, in this case, TikTok.

US restrictions on foreign trade are restrictions on Americans.

>Americans have the right to trade with foreign companies

Err, foreign affairs (and thus commerce) has always been something regulated by the US government - something reserved for the president unless the legislative explicitly declares otherwise. Source: https://www.law.cornell.edu/constitution-conan/article-2/sec...

Do you know any constitutional clause or SCOTUS case suggesting otherwise?

There is no right to trade with foreign companies. Try doing business with a North Korean company and see how that goes for you.

Americans have no such right — the US government has the authority to impose economic sanctions on foreign governments that explicitly prohibit doing business with their companies.