My 2 cents, and would love to hear other thoughts, is that we are entering a wholesale recalibration moment. If we were new to using desktop computers in the 80s and 90s, we'd be having a similar conversation - with these new tools, how do I do the job I'm familiar with? Is this even the right job anymore?
Product Managers, Software Developers/Programmers/Software Engineers, and Product Designers are all relatively new professions. It does look like we are entering a phase where all of our lanes will be redesigned.
The customer will have whatever expectations your team is setting, and I'd assume teams are syncing on product objectives and not working in silos, so I wouldn't worry so much about an interactive prototype, or polishing someone else's UI. I would be looking for higher value tasks - like strategic alignment, design systems, consistent components, and coaching/critiquing anything that interfaces with the user. As a PM, if I have been iterating on UX concepts based on user interviews and other data, I'd love to take those prototypes to a product designer who knows the user well already. That's a great first sync. Not to get pixel edits, but refine the experiment that is about to be tested.
