[hardwaresofton]

Here are a few that are in the ball park, but mostly lacking the form bit (you have to make your own though most of these offer a way to have a append-only user for the form to act as):

- Strapi (https://github.com/strapi/strapi)

- Directus (https://github.com/directus/directus)

- React Admin (https://github.com/marmelab/react-admin)

- Netlify CMS - a bit off the mark but maybe worth considering (https://github.com/netlify/netlify-cms)