@JP *********
yes there are ways to minimize taxes including to zero. FEIE and FTC being the two main ways to do so.
But you can’t get rid of self employment tax in most cases so if ever self employed she would owe that. Also the higher the income the more likely someone will owe.
And she would still be required to deal with FBAR and issues with banks not opening accounts. Which is the main reason people get rid of US citizenship if they are not wealthy.
In general anyone with another passport, especially a strong one, that does not truly plan to live in the US is best served by getting rid of a green card or citizenship.
The US tax system is annoying if you are not dealing directly with US incomes, banks, investments, and etc.