Microsoft didn’t do a great job of announcing the side-by-side viewing feature for Microsoft 365 apps. It seemed like the only reason for the feature was to drive usage for the Edge browser. As it turns out, you can choose to have Microsoft 365 apps use a different browser, and the tools to do that are now available.
https://office365itpros.com/2023/05/25/side-by-side-viewing-m365/
