Making a lot probably means it's not a side project anymore. Do you mean side to begin with, or ongoing? The latter will limit the attention you can give it.
So I was wondering if it's a viable strategy to build a complete product, end-to-end and put it out on the market for someone else to purchase and operationalize.
I think "side-project" is misleading. What I really meant was "quickly buildable" projects. Some examples of such projects would include a unique LLM-powered content generator, or an AI-based Google Forms, etc
remove.bg is a good example of a project in the lines of what I have in mind.
Check out Rob Walling and StartUpsForTheRestOfUs, great podcast and lots of great advice.
Check out his stair step approach. Basically start out with a simple product. An info product, plugin or package and then keep leveling up to get to a SaaS.
Good luck, keep those resumes going out.
But you already told us you don't.
Have a go, but you should stay focused on getting a job. It's, unfortunately, a numbers game. I don't know your situation, smaybe you don't really need to yet.
But I did something similar when I got laid off in 2008, and in hindsight it was a massive waste of time and a way of making myself feel better without doing something actually productive to get a job.