https://a.co/d/fsUPIlH is what I bought. Amazon has hundreds of other bands also. You can also get an adapter that allows you to use any standard 20mm watch band- https://a.co/d/hdBiCN7

There are tons of aftermarket bands for Pixel Watch on Amazon now. I bought one that is a lot more ventilated and doesn’t irritate my arm with constant wear like the band that came with the watch.