Reddit mentions of Bluetooth Receiver/Car Kit, Bluebyte Clip Bluetooth Receiver for Headphones or car Audio,Wireless Audio Adapter Support Hands-Free Calling,Bluetooth 5.0 Low Latency for Music(Black).

The options on the Pixel 2 are either, get 2 USB-C to 3.5mm adapters, replace headphones with Bluetooth versions, or buy Bluetooth receiver adapters for your headphones (like BlueAnt Ribbon). The USB-C adapters are nice, but you lose the ability to charge and listen at the same time. Also note that you need a Pixel compatible USB-C adapter (not all are).

While you may not think there was a reason to remove the 3.5mm, the reasons are:

• it removes a fair amount of the interior of the phone, leading to more room for other components or battery
  
• it allows for thinner phones (the headphone jack was the thickest part after the switch to USB-C by a full mm)
  
• it removes a hole into the phone thus making it pass water and dust tests more easily
  
• the headphone jack was the most likely thing to break on the phone as it can easily be torqued (this is why Apple had that thinner casing to provide slight strain relief)
  
• no headphone jack means the screen can get closer to the edge (less bezel)
  and Finally
  The quality of the audio through your headphone jack wasn't as good as you think. It was still a digitally compressed signal going over decoder, DAC, and amplifier before being sent over your headphones. The OG Pixel apparently sounded pretty bad over the headphone jack. The USB-C adapter has a decoder and all built into the adapter (hence the incompatibility with some adapters). There's also the fact that aptX compression is pretty high quality (close enough you'll almost certainly never notice unless playing FLAC files and probably not even then) and current aptX Low Latency versions are within broadcast television audio/video sync time.
  
  https://www.amazon.com/dp/B06WVGTH2D/ looks like a decent choice.
  
  Finally, camera comparison. Note that there's better software than the stock one available now that will bring them closer as Google is pushing some of the algorithms of the Pixel 2 to other phones. That stated, the Pixel 2 is typically the top rated Android camera (losing only to iPhoneX typically). The big advantage of the Pixel 2 isn't the quality, but the speed. It can take pictures as fast as you can press the button (as it's really in burst mode anyways and just changes the duration of the burst).
  https://www.tomsguide.com/us/pixel-2-vs-moto-x4-project-fi,review-4848.html
  
  In the end, the Pixel 2 is a premium phone at a premium price. The Moto X4 is a mid-range phone at a mid-range price. X4 is more bang for the buck and Pixel 2 is the luxury model. Both are very good for their level.