I'm currently building a site using actix-web, which relies on the http crate for strongly-typed header constants, and I noticed that there are a couple of headers which don't yet have constants here, forcing me to resort to manually specifying them as strings.
Specifically:
As these headers need to be set to enable access to browser features like SharedArrayBuffer and un-throttled performance timers, I think it'd make sense to add CROSS_ORIGIN_EMBEDDER_POLICY and CROSS_ORIGIN_OPENER_POLICY constants.