I just figured out this issue I was having with the install so I just wanted to share how I fixed it!
The Problem
I was having issues when I was flashing my Pixel 6a with my Macbook, where my flash would stall indefinitely on the fastbootd screen on the phone, with "Restarting device..." on the website. The last message in my Chrome DevTools says, "USB device disconnected".
The Cause
MacOS has a setting called "allow accessories to connect to Mac" that is, by default, turned off so that you have to manually accept each new device connection to your Mac. As a result, when the prompt appears to allow the new accessory, it disappears before you can click "approve" (because in the process of flashing your device is disconnected and reconnected multiple times), and therefore, your flash is stalled.
The Solution:
To fix this, you must change this setting in your Privacy settings to be "Automatically When Unlocked" or "Always" to allow accessories to always connect without manual approval, and try again.
Hope this helps! Grateful for everyone who has made this OS and contributed to these forums!