Cross-origin isolation support in Excel Online

We were considering using SharedArrayBuffer for certain optimisations in our add-in.

However, it seems that strict cross-origin isolation is required for that to work. https://web.dev/coop-coep/

globalThis.crossOriginIsolated returns true in Excel Desktop for Windows, but it returns false in Excel Online. Can it be supported in Excel Online, at least in theory?

This is the future of the secure web and will increasingly be a requirement for organisations.