Shameless plug: If you want a static site generator with an admin UI I can recommend Lektor (https://www.getlektor.com/). You declare your data model and templates and Lektor serves an editing UI for you. There is a good video introduction by Armin Ronacher (original author) if you prefer to digest video content: https://www.youtube.com/watch?v=lTWTCwuPdrU

Disclaimer: Occasionally I moonlight as a maintainer of Lektor.