Do you buy the domain for your landing page?

I think the most common piece of advice I see/hear in the IH community is to validate first. One common way to do that is to build a landing page for your idea to collect interest. Taking money is best, but taking emails is better than nothing (usually).

There's plenty of ways to quickly and cheaply/freely build and publish a landing page for this. But, do you go ahead and buy the domain for your potential project to point to the landing page, or do you put the landing page at some arbitrary URL (i.e. myproject.netlify.app)?

Of course, buying the domain seems like a good idea. You can avoid someone else grabbing it after seeing your landing page, and it provides more consistent branding and feels more legitimate. But, it's also extra steps and money before you've even validated your idea.

How do you approach the landing page validation?