In number the great bulk of projects I see are small maintenance or minor enhancement projects. They’re done in a day or a week or two by a single developer. Adding anyone or even the overhead of something like Scrum is counter-productive.
My assumption has been you hand off the assignment and let the individual self-organize with say a business analyst, QA person, and maybe a PM. I wonder if they’re aren’t some emerging ideas on how to handle this from the Agile community. I know some people organize a maintenance list and just pull things off a prioritized backlog when they have downtime.
The best way to tell if your one developer project is Agile. The developer and business analyst meet the documentation requirement by emailing back and forth a one page or less document and the PM runs it around for signatures a bit before or sometimes a little after the code has been pushed out to production. The only thing we typically miss is some way to do an inspect and adapt cycle.