Royal absolutely does 1 way cruises between Vancouver and Seward on the Radiance. They didn't do it this past year due to covid. However, the Radiance is scheduled to resume those itineraries. The itineraries are offered in both directions. If you do the northbound itinerary, you would board in Vancouver and you could get off the ship in Juneau without violating any cabbotage laws. The problem is that Juneau would be the first stop. So, you would only be on the ship 2 nights before getting off. It might be better to fly to Juneau first for a couple days, then fly to Anchorage take the southbound itinerary from Seward to Vancouver on the Radiance.