See linked article above, you have an adapter that works with your phone, but it might not work with your friend’s phone, or your friends’ adapter/headphones may not work with your phone, and if your adapter breaks and you replace it you’ll need to be careful with finding a compatible replacement. With lightning headphones and adapters they’re all just compatible.
I don’t know anyone with Pixel earbuds, but their reviews online aren’t stellar.
Ok, they're compatible with phones that have a lightning port. Unlike the USB-C "one port shape, a million devices and cables implementing various optional subsets of the specification" compatibility mess.
As long as you use the cables that came with each device, you're great. If you're buying aftermarket accessories, research carefully, and best-case find a review from someone with the exact same set of devices and cables.
I say this as a USB-C laptop owner. The either-orientation plugs are great, the charging from whichever side of the computer is more convenient is great. But just because a cable says it supports DisplayPort alternate mode with multi-stream transport at 4K/60Hz doesn't mean it's going to work.
EDIT - actually more to the point, just because it has USB-C at one end and DisplayPort at the other, doesn't mean it supports multi-stream transport at 4K/60Hz. Right port shapes? Check. Does what you expect it to when you plug it into your gadgets? Flip a coin. And then put your screen into DisplayPort 1.2 30Hz compatibility mode and pretend the low refresh rate doesn't bother you. It's a standards compliant cable, just not the right part of the standard.
I don’t know anyone with Pixel earbuds, but their reviews online aren’t stellar.