Very close to this issue, but not quite the same ask. This encompasses it though - you may want to move it here. Moved and elaborated on from my Discord message.
Lockdown Mode is a feature in macOS, iOS, iPadOS, and watchOS that enables "extreme protections that’s designed for the very few individuals who, because of who they are or what they do, might be personally targeted by some of the most sophisticated digital threats." In non-marketing speak, this is designed to reduce the attack surface of your browser to protect against a future attack on your device. It was (most likely) made in light of Pegasus.
Apple describes that "certain complex web technologies are blocked, which might cause some websites to load more slowly or not operate correctly. In addition, web fonts might not be displayed, and images might be replaced with a missing image icon." On iOS, iPadOS, and watchOS, this applies to ALL browsers due to their reliance on WebKit - however, on macOS, you're free to use whatever browser engine you want.
When Lockdown Mode is enabled, a TON of WebKit settings are adjusted:
All of these changes are open-source. I think it would also be beneficial to remove the window.KAGI
object in Compatibility Mode while Lockdown Mode protections are on.
This will impact existing workflows and the overall user experience, but only for those who are using Lockdown Mode. I expect some may be using Orion as a Lockdown Mode-free browser, but that ultimately defeats the purpose of Lockdown Mode (and shows they're missing the point completely of what it's for!)
This feature will likely help more people move from Safari. I believe Orion would be the only other browser to fully implement and manage Lockdown Mode (besides on iOS, iPadOS, and watchOS, where it's not really possible to do it like Safari does until the inevitable comes. In combination with Compatibility Mode (to blend in more with Safari), this would be a great addition to get to the point of having one browser for everything.