Anyone have any idea

Speaking in Backbone terms: Yes you can just change a view's template property any time before the render function is called. Then SCA also has some capabilities with Site Management tools to do this by configuration but i'm not familiar with that enough to say, but you can search around the help, i believe it was relased in 2019.1 and enhanced in 2019.2

I guess it depends on where you want to run your validation checks for rendering the template. I did try something similar in ProductDetails.Full.View.js (initialize function) and it works