However, after creating an account, I cant find a way to upgrade the product from free file based on online instructions (no Upgrade button showing) and the only way to reach a human seems to be calling a US number while abroad (which after waiting for 2 hours on hold I gave up on). Is there a way to get in touch with Turbotax via message, or to find out whether or not I need to file from elsewhere ? Thanks in advance for your answers.
There are so many factors about if you need to file a 1040 for residents or 1040NR for non-residents.
I advise you to start with our partner site, Sprintax. They handle the filing of 1040NR.
They will take you through a series of questions to determine how you should file.
If you need a 1040, they will refer you back to TurboTax.
Follow this link to get started: Sprintax
However our partner Turbo tax specializes in tax returns for US residents