compel” limits bit is limited to US citizens

This is completely not true. The 4th and 5th amendments apply to everyone.

that even then, they can confiscate your phone

If they do this without getting a search warrant from a judge, you can sue for the return of your property. You can make them justify to a judge why there is probable cause that your property will yield evidence of a crime.

they can refuse to let you fly

This is a thing that can happen, but you can also sue the federal government to challenge your wrongful placement on the no fly list. People have sued and won and been awarded costs and attorneys' fees

confiscate your passport,

This can happen if they think the passport is fraudulent, invalid, expired, stolen, or if you owe taxes, or are a sex offender that needs an annotated passport, or sadly if they think you are trans.

For many of these causes, the simplest solution is to apply for a new passport. For the trans victims, the issue is currently in federal court, and I am hopeful for a positive outcome.

deport you to the country of their choice.

At this point I assume you are talking about non-citizens, non-LPRs. If such a person is refused admission they are preferentially deported back to wherever they came from. At land borders, that is cheap and easy. Air carriers are required to transport passengers back to origin at the air carrier's expense when CBP so demands. (This is why airlines check your documents thoroughly before they let you go.)

If for some reason the person's travel origin refuses to accept them, then the next preference is a country where they have citizenship or strong residence ties.

With the exception of the original set of CECOT flights, which were done in actual contempt of court, true third country removals are the last resort both in law and in actual (however fucked up) practice.

The people who have been sent to the strange African countries have problems with no documents, no proof of citizenship, their true home country refuses to accept deportations from US because of bad relations, or they have withholding of removal because of a legitimate fear of torture or persecution in their home country. That's not something that's going to happen to the vast majority of people that show up at an airport with actual good documents.