Originally Posted by Kongduino

For scenario #1 I don't see why not. The main issue will be interlining, for your luggage. But CX and JL interline (or used to before Covid, at least), so this shouldn't be much of an issue.

For scenario #2, the issue will be the luggage indeed. ANA and CX don't interline, AFAIK, and you won't be allowed to pass through Immigration to pick up your luggage, then onwards through Customs, to go upstairs and check in again. There's no "quotes" about entering the country – you would definitely enter Japan...
It would be nice if NRT and/or HND had a luggage retrieval service like in HKG for the ferry, allowing check-in without entering the country... But, such a service would probably a huge mess to organize...