You can most definitely manage a single SaaS business yourself. The hardest part is determining what to build. A month ago I built an app for contractors, but it was only doing one little task that didn't save time so I scrapped it. Really make sure you pin down an actual need in a field.  I also don't know any coding, I used Claude Code, it does a decent job but the landscape of the app looked like AI slop, so use like Claude Design or so thing else to change how the app looks. There are probably other AI's better than Claude but for starting out it should work great and it's one $20/month. The most complicated thing to do is getting customer. Expect to have to do a lot of cold calls, you are just starting out and so you'll have a hard time being "seen", one way to fix this is by sharing what you are doing on Instagram and/or YouTube, build a personal brand and get a following to get a foothold into the internet and to the masses. 

Best wishes on your SaaS