Even if Windows offers this possibility, the traditional behavior of applications on MacOS, and Apple's interface guidelines remind us, is to have an application open only once, with a single icon in the Dock. To have multiple instances, just open new windows in the app. This is what Safari 17 does and respects with its profiles feature.
I think Orion should take this principle (there are still ways to improve and offer something different from what Safari 17 offers while respecting the principle).
There can potentially be a few performance consequences (defining what is meaningful for an Apple Silicon machine), this can protect other profiles if a profile/website/... crashes and allow continued use of Orion (if we have multiple profiles open at this precise moment), but these are generally rare phenomena in our daily use; which in any case does not prevent the crashing of the profile and its relaunch, and there are mechanisms to find our sites/profiles etc. precisely in the event of a crash.
The keyboard shortcut command+tab would certainly no longer directly offer the different instances/windows of the profiles but only the Orion application (same principle as for the other macOS applications) but it would still be possible to access the Dock directly via the icon of 'Orion has all open profiles (which Safari 17 offers) :

Also, advanced command+tab users are usually already using utilities to enhance this functionality and directly access a window, profiles, etc. (apps like Command-Tab Plus, BetterTouchTool, for example).
And Orion's "Session tabs" feature, combined with profiles, I think already answers a large part of the problem of the data sandbox.