Checkout – Perception of progress – Number of pages

I am at the beginning of redesigning a shopping / bag page and I thought about how people perceive their progress through a form based on the amount / lack of pages.

We currently have a bag page that clicks through the box, the box is a single page.

My plan is to combine the two on a single page and integrate the login process for users without an account (you need an account to complete the purchase).

Would users feel they are progressing more towards their goal if they navigate from page 1 to page 2 or if the fact that they only have to complete the actions on a single page to achieve the same goal makes it seem faster?

So in summary, do I go for two short pages or a long one?

(The page load of the long page is not a problem, the difference is inevitable)