Landing page for idea validation - which tool?

Hi all!

We're working on an idea because we have explored an interesting problem domain. Now we have 3 different approaches to the problem that we know are all feasible.

I would like to build a landing page for each solution to use it for

1. qualitative feedback (show it to the target audience) and
2. quantitative feedback (send traffic to it and see which solution converts best).

My background is tech, but not design. Not comfortable in Figma. My preferred options are:

• Buy a bootstrap template and customise it
• Use a SaaS

Which SaaS would you recommend?
I've looked at Mailchimp landing pages, unbounce, instapage, and webflow.
The techie in me prefers to just buy a bootstrap template and throw it up on Render.

Would you buy a custom domain for each solution, buy a single one and host the 3 solutions on subdomains or don't bother with a domain at all?

Thanks HN for your input!