Huh, FATCA means you can't have a savings account? I'm also a US citizen using N26 in the EU and hadn't realized that - thought it was because I wasn't in Germany. I haven't pursued savings mostly because the rates are pathetic.
Living and working in Asia for many years, I always sympathized with the difficulties my American expat friends had in trying to open any sort of local bank account at all, even a current account. Most banks say no the minute they hear you're a US citizen.
Not being able to open a bank account in the country in which you live has serious knock-on effects in terms of getting paid, or renting a home. I am eternally amazed that American citizens, who supposedly value personal freedom, put up with having one of the world's most aggressive tax regimes.