What kind of software can be realistically built for clients by a self-employed solo developer in part-time?

Hi,

I’m a front-end web developer working on a team, contributing to development of smaller parts of complex software. I’d like to transition to a self-employed, end-to-end (full-stack) software developer role, where I would handle everything from requirements to delivery, all on my own. Which types of projects can a one-person shop realistically tackle? I'm interested in smaller projects with relatively short time-to-market, that can be done part-time.

Thanks in advance for your suggestions!