Can I use an mpp file in the new Planner app? I have a file that is a template that I want to share to other project managers

Question

We recently promoted the MS Project for the web tool to our community of Project Managers at our organization. Previously, I instructed them use a specific .MPP file as a template that they could customize. Now that we are moving to MS Planner in August, I see this feature is no longer available. What is the easiest way that I can hand off a default project template to our Project Managers? I don't want them to use the provided templates, rather a customized template that I developed for our own pm frameworks at our organization.