checkout – Perception of progress – number of pages

I am at the very beginning of redesigning a payment / bag page and have been thinking about how people perceive their progress through a form based on the number / lack of pages.

Currently, we have a bag page that clicks till the checkout, checkout is a single page.

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

Would users feel that they are making further progress in achieving their goal when navigating from page 1 to page 2 or that they should only perform actions on a single page to achieve the same goal gives them air faster?

So, in short, do I choose two short or long pages?

(The loading of the long page is not a problem, the difference is imperceptible)