I'm traveling to the US mainland for the first time in my life in a few weeks.
I am not overly stressed about privacy, but I have read that US immigration can really overstep their boundaries. Are there any simple specific steps to take on my devices to protect my privace when going through US border control?
Remove my main accounts from my phone/tablet and use dummy accounts? Or just removing my biometrics?
If you are doing something illegal then you should definitely bring a new device. If you are not doing something illegal then you should just bring your normal device and keep it locked/off when entering.
They can force biometrics but not pin, but they will only do that if you're already in super deep trouble for breaking the law. Just be normal and you'll have no issues.