Hi Joe, you need to pair both buds, but then you can use just one bud if you want. You can just wear a single bud.
To get hands-free help from Google Assistant. This link might be helpful: https://support.google.com/googlepixelbuds/answer/7560032
You may also check this link about managing phone calls with Pixel buds, this includes making a phone call with Google Assistant: https://support.google.com/googlepixelbuds/answer/7559108