How can I use Javascript to determine if an Edge Chromium user is logged in or not? I can use a trick to do this on Chrome and then present them through a flow to create a Google account, but cannot use this same technique for Edge Chromium users to create a Microsoft account.

However, I did notice that Guest Mode on Edge Chromium will show navigator.languages to have 1 entry for our website, while logged-in mode will show 2 entries. However, Guest Mode is not the same as logged-out mode -- it's just another form of logged-out mode. I logged in my Microsoft account and then logged out in Edge Chromium (thus, turning off sync), and this navigator.languages trick for our website didn't work.