Yes, every journal in the world will happily accept "research as a leisure activity" if your paper is high enough quality. The quality bar is somewhat higher t

Yes, every journal in the world will happily accept "research as a leisure activity" if your paper is high enough quality. The quality bar is somewhat higher than if you are in the academic-industrial complex (like it or not, people can recognize authors by writing style even on blind review), but you are able to do and get through peer review as an independent researcher. Be prepared to be underwhelmed if you are doing it for the publication, though. Most published papers don't lead to anything. Do the research for fun, and publish to share your results. Actually, if you are a small "research for fun" shop, you can target tier 2 journals and conferences, and you will run into an enthusiastic community of people in your subfield. Of course, this depends on knowing how to do new research, write research papers, and talk to peer reviewers. That is the bigger barrier to entry.