Users have already verified that this works on a basic level -- you can use the Pixel 3's USB-C headphones to translate on a non-Pixel phone. The question is whether or not translation works as seamlessly with third-party audio. LG's Tone Platinum SE has a dedicated Google Assistant button with translation support, but that wasn't a promise of universal access. Now, Google is making it clear that it wants a whole ecosystem of headphones that can translate on the spot.