Comment by t_mann

You seem to equate research as a leisure activity with amateur research. If you read 'leisure' simply as 'outside your main, bread-earning job', then it absolutely can be cutting edge research published in peer-reviewed outlets. It's not even that uncommon, look for people who have a university affiliation (that isn't just teaching) as a side gig. And that's just one way you could be pursing serious research outside your main job, you don't even need a university affiliation - it's certainly helpful with access to resources, feedback, ideas (and, let's be honest, it probably helps with visibility/credibility too), but it's not strictly necessary. As a different example, there are some (rare) examples where legitimate mathematical results were discovered by hobbyists going completely on their own. I also remember a documentary about a crew of retirees, including former physics professors and a precision mechanics engineer, who were performing physics experiments of masses at extremely low accelerations to test some limits of special relativity iirc - which in itself was technically the result of 'leisure research', like several of Einstein's most famous discoveries.

If it's something you're interested in, my suggestion would be to decide on a rough area and then seek out experts to brainstorm ideas for a suitable problem for you to work on, maybe one that leverages your existing skills in a creative way (like the engineer in the above example).