I separate mine for proper management, and housekeeping.

Landing page (website.com) is always changing (refining value proposition, marketing experiments, pivots, etc.). Also with VA/marketer in mind, easy for them to manage. I play around with both code and no-code. So it won't touch the app side of things.

And it can be the other way round as well. I might want to experiment with different middlewares or backends.

At least you don't have to change the whole thing.