The problem[Edit]: CORS is that you are not yet signed into o365 and you are unablehappening here... You wont be able to access the search there since you are missing the right cookiesSPO from your onprem... Sorry
You either need to authenticate the users vs the endpoints you listed, or anotherAanother approach could be to connect your O365 search to your local farm in a hybrid scenario by consuming their index. That would allow you to access the information as if they would be hosted on your search service. This wont work for delve access thought, since that's only available online.