The approach I have been taking of creating a new page for each version of Chrome OS is getting out of hand. I've decided to create this one page and use page folds to denote each version.
Version 88
Version 88.0.4324.109 updated on the Google Pixelbook the evening of 2021-01-27. I do not yet know what is different of note.
Screen record (video) is enabled, although it currently does not record audio. ChromeUnboxed 
chrome://flags/#screen-capture
New lock screen settings are available when you enable the screen saver, select Personalization > Screen Saver.
A scanning tool has been added, which you can enable via the following flag. I've enabled it but it doesn't appear to discover my HP Officejet 6700 that has a scanner.
chrome://flags/#scanning-ui
A Reading list icon can be added for web pages flagged to be "read later." Think of this as a scratchpad for bookmarks. I've also enabled this in Chromium on my desktop.
chrome://flags/read-later
Version 89
Chromebooks turn 10 today and Google has coordinated the celebration to coincided with the much-anticipated release of Chrome OS 89 ChromeUnboxed Watch a video overview of Chrome OS 89 by ChromeUnboxed.
The update is now installed on my Google Pixelbook and my Lenovo Duet.
One of the "new" features released in Version 89 is the screen capture function I enabled in Version 88 by a flag. Now there is a Quick Setting icon to initiate the screen capture, that includes screen recording.
Another useful feature is the ability to pin files to the dock, which is called Tote . Chrome automatically pins recent screen captures and downloaded files to the Tote.
The contents (apps) assigned to Virtual Desktops is supposed to persist after a reboot but they don't on my Pixelbook. Not sure if the problem is with my expectation, installation, or if there is a bug in Chrome OS.
Version 90
This version of Chrome OS was released to the stable channel on April 21, 2021 and available for update on my Lenovo Duet and Google Pixelbook. Key new feature is the change of the Launcher button to the "Everything" button, that can now be used to get information like the weather in additional to searching for apps and web sites. I don't think the Everything button is working as described on my Pixelbook. For example, I type weather and I still just get search results. I've also read that YouTube and Google Maps are supposed to launch in windows rather than browser tabs, but they are still launching in tabs.
The Diagnostics app is now more polished and available in the launcher.
This release also officially launches the Scan app that still doesn't recognize my HP Officejet 6700, which is a multi-function printer that includes a scanner, as a scanner.
An experimental feature that allows you to create a link directly to text in a web page is available by setting a flag . <-- Click this link to see this feature in action.
Android Police has a nice run down of the other features in this release.
Version 91
Version 91 released to stable channel on June 1, 2021 and was available on the Lenovo Duet and Google Pixelbook on that date.
Key new feature is the official release of Nearby Sharing, which I have tested with my Pixel 4a and both devices. Also includes app icon notification badges and new wallpaper.
Version 92
Version 92 released to stable channel on August 2, 2021 and available on the Lenovo Duet on that date.
Key new features include redesigned emoji and emoji picker, rick-click Android or Linux app window to move to a different virtual desktop, Tote shows Android app downloads and Chromes Print to PDF, Chrome OS Camera App supports pan, tilt, or zoom, and new "Togetherness" wallpaper.
Version 93
Chromebooks will now (September 8, 2021) begin receiving an update to Chrome OS 93. there is a focus on polish and streamlining the user experience. ChromeUnboxed I now have this version running on the Lenovo Duet and the Google Pixelbook.
I am noticing that the Files app is taking a long time loading the file system for display. I am also seeing this in File Save dialogs. Not sure whether this is an issue with Version 93, but I don't remember seeing this problem before. A similar report suggests the problem is due to SMB shares and the only fix is Powerwash!
I have two SMB shares that I created in Files that are not responsive. Click on them and nothing happens, so I imagine the app is trying to load them and then timing out. However, I realize that I also have shares set up with Linux (Crostini) so I decided to remove them first to see what happens. Alas, that did not work. The problem with powerwashing is that I will lose my Android and Linux app configurations, although I can back up the Linux container. I have, however, powerwashed the Pixelbook and the restore was not as painful as I feared.
**Note:** Google is decreasing the time between releases of Chrome and Chrome OS from six weeks to four weeks. The change is happening first with Chrome between versions 93 and 94. For Chrome OS the change will be between versions 94 and 96, **with version 95 being skipped**.
Version 94
As of October 16, 2021 version 94 has been released to the stable channel . The only changes of significance to me are flags for App Launcher sorting and new Bluetooth settings. So far I have not been able to get the app launcher flags to work.
One of the most interesting things about this release is that it begins the separation of the Chrome browser from Chrome OS . Ever since the beginning Chrome OS and the browser have been the same thing, but Google is going to separate the two so that changes to Chrome can be released faster than changes to Chrome OS.
Version 96
On December 1, 2021, ChromeUnboxed reported that Version 96 has started being pushed via stable channel. source
After an initial release last month, then getting pulled, the Chrome OS 96 update is back. Google restarted the rollout to Chromebooks earlier this week and a few of my devices have already been upgraded. About Chromebooks
Includes an update to the Camera app so scan documents and QR codes. Nearby Share can now share to Android apps. A new wallpaper picking experience is also included.
I've enabled reader mode and the productivity launcher following the instructions provided in the About Chromebooks page.
Version 97
Version 97 released to stable channel on January 7, 2022. source
As of January 10, 2022 this version has not yet been released for the Google Pixelbook but it has been pushed to my Lenovo Duet.