Thanks for your patience while my team looked into this for you.
While you can use the deploy to Netlify button without the netlify.toml
file, it won’t serve your needs here - without one, it would assume the base directory is the repo root, and it would try to infer the build settings, so it would never find your subdirectory-based site(s).
I’ve filed a feature request for you and will let you know via this thread in case things change in the future, but i don’t see that as likely to happen in the near future, so probably not best to plan on it.