Yes, this also. In my organization, we have a problem with "just ship something" because the cost of making a release is so high. We know this, so rather than ever "just shipping this part that's ready" we often drag projects out longer so we can "be really done with them."
Only sometimes, we could really have been done with them, without necessarily finishing all of that pet feature which has thrown off the whole timeline, by being more complicated to implement than anyone was able to imagine upfront.
I’m not sure I understand how they interact. My teams have always continued to practice continuous delivery totally independently of sprint boundaries - that is, released were totally independent of sprints.
Yes, that's how it should be and basically it sounds like you are then already doing a Kanban style working mode (and what purpose does the sprint rhythm than serve)?
Scrum by the books usually implies that releases happen after the po or the customer has accepted the increment at the sprint review.