It is not your role to move this forward. This is part of a large struggle for control between different parts of your org. In a good org this would bubble to

It is not your role to move this forward. This is part of a large struggle for control between different parts of your org. In a good org this would bubble to leadership and get decided in a poor org blamed gets passed so do what you can to avoid being labelled as the cog. The pm is doing a poor job here. This person needs to meet with the boss of services and let them know the priority and buyin of the project at the leadership level and let them purpose a solution (like a new service)