How to prioritize a block when rendering?

Question

JavaScript

Good afternoon, there is a regular page with information about the product, it has an order form.
It is necessary that the form is displayed first on the page when rendering (if the Internet is slow, there is no memory, etc.), then everything else is already loaded.

How is this possible to do?
So far, there is only 1 option in my head:
Light version of the page - where there is only a form, after the page is fully loaded - rendering the full version of the page.

Am I thinking in the right direction?
Are there any other options?