I went all in for project templates for my organization in ArcGIS Pro until something went wrong creating a project template. Then I started to think about why my organization needs a project template and why we can't just use a read-only project.
Anyone that can list the pros and cons with project vs. project template?
You did go through the sections in the help?
Project templates—ArcGIS Pro | Documentation
So what went wrong would be more to the question? Any particular component of what a template provides that a saved project solved? It may be easier to address that issue.
In this case the added layouts seemed to be the issue, I haven't figured out if it is too many or if something is wrong in one of them. But before I spend a lot of time testing I would like some input if a project template even is necessary.
Not necessary at all, it is a convenience largely. If the layouts are an issue, they may persist whether you use a template or a standard project.
Avoid including data, data sources whose location may change or is not accessible to all people in your organization would help. If you have a base map for your organization, make sure it resides locally (on server perhaps) rather than relying on external sources. etc.
Also, the less you include, the better, don't try to provide a template that covers all users.
Other elements, such as layouts, can be 'templated' and stored for access to people that need them
Mine is a version of the original question.
When/why to Template and when/why to share as a project?
My goal is a ready to distribute, a something, such that another person can run the project/template with new data and the rest existing features, tools, symbology and etc? I cannot know if there will be a path back to the original database, tool set or whatever, but the new map builder should have in particular: tools/models and preexisting feature classes.