Allowing custom views to take advantage of all Next.js app router features

[tyteen4a03]

Currently even in v3, the way to specify root views is still very similar to how it's done in v2, which means custom views can't take advantage of Next.js features as we're essentially limited to having a single page.tsx to render our views. This makes building out new views that also take advantage of Next.js features (filesystem-based routing and use of layout.tsx being big ones) fairly annoying to do.

I'm not sure how to improve on this situation (especially considering the other discussion I opened that would make (payload) sacred), so just throwing this out there to see if we can find a solution somehow.