I'm a PM with PO work.
I'm responsible for laying out the product roadmap and get the agreement of stakeholders about the priorities.
Then, I create the Jira cards with the context, request, supporting materials, and acceptance criteria for each feature.
Then, I meet with my tech lead to go over the sprint planning.
I explain the features and the cards. We discuss potential issues and keep each other in sync so that if the devs have questions, I can make the decisions.
He worked with his team on what can or cannot fit into a sprint. Things that don't fit are moved to the backlog or the next sprint.
He spends time getting his team to start and finish the sprint. Once the sprint is completed, I have the new feature in the beta environment to test against the acceptance criteria.
If everything is okay, I approve the release to UAT/ PROD.
There is no blur between my work and his work.
A potential blur can happen if the PM/PO is not the one creating the request and the acceptance criteria. It can happen. I ask for a product/ feature. Define high level, and the devs come back with something. That usually happens with new products or heavy back-end stuff.
My Jira Card Template:
Context: describing the business needs, user stories, or issues that a user is encountering.
Request: section where I ask what I want the devs to do from the outcome perspective; it's essential not to tell them what technically they have to do unless it's a bug.
Supporting Materials: it's the section where I attach my supporting files such as screenshots, mocks, and users feedback.
Acceptance Criteria: it's the area where I list the steps of what the user should be doing and the expected results.