Concept is great; so much work can be done in just the browser these days, so it’s an ideal place to be looking at. However, I think customers should perhaps first concentrate on reducing the number of browsers in their environment and then look at the tools they’re already licensed for.
Multiple browsers increases your patch footprint, so reducing corporate devices to a single browser will help reduce complexity. For M365 customers that’s obviously Edge and Google Workspace it’s Chrome, of course.
Depending on what you’re already licensed for, you may have access to the Citrix Enterprise Browser or Microsoft Edge + Defender for Cloud Apps (more complex solution, but it can be configured to protect corporate apps).
After that, then perhaps look at dedicated enterprise browsers such as Island.