Found the reason for why the Chrome OS Files app on my Pixelbook was taking so long to load the file system. There were SMB share mappings that became corrupt and basically Files was trying to access those shares but would eventually time out. Unfortunately, the corruption prevented me from removing the shares via the UI and there is no known way to manually remove them, so I had to powerwash the Pixelbook.

Powerwash restores Chromebooks to their factory default state, and because all of the apps and settings for Chromebooks are in the cloud, the restore process is pretty quick, even with Android apps installed. If you do have Linux apps installed, which I do, that does require a traditional backup and restore, but restoring a container such as Chrome OS uses for Linux makes that restore process pretty quick and straightforward.

My personal experience with this process confirms to me why Chromebooks are so popular with schools, the restore process for them is probably the easiest and fastest of any device you can put your hands on.