We want to start a public community but also have some sections viewable by staff only. Is this something that can be done with a single install? (I am aware that I could also setup two discourses with one set to public signup and another by invite)
You can absolutely set up categories that will be accessible by staff only using group permissions! We do have a video here as a reference: [Video] How to create a private category using group permissions
Hope this helps!