I can’t speak for Chrome’s plans.
We’re developing an improved install flow for mv3 extensions, and if your extension only requests a few specific domains (so not <all_urls>) we’ll make it easier for users to grant that during install (likely checked by default).
Note that we don’t plan to revert any behavior in Firefox, so users could still decide not to grant those permissions (or may revoke them later), so your extension should still account for that, check and ask for any permissions it “needs” to function using the optional permissions api.
Hope that helps.