I think he's referring to audio accessory mode not being supported, meaning you need a pair of active headphones (which those Sennheiser's are). This will probably still be the case, though I haven't seen anything definitively about the Pixel 3. Motorola is the only company I can think of that supports passive headphones through USB-C.
If you're talking about HTC's implementation for Noise Cancellation, etc., that's even less likely as that is essentially how they wired their USB-C port and because it's not standard, most manufacturers won't follow that.