Although you'd be denying yourself some native features of Forest Admin (CRUD), this may be mandatory for you because of your project's architecture or security requirements.
To set up Forest Admin with a read-only database, follow those steps:
A collection can be set as read-only from its settings, accessible using the Layout Editor mode:
You must disable all permissions there, as described in this section.
At this point, your Forest interface allows you only to browse your data and not interact with it.
You still have the opportunity to interact with your data according to your processes with a little coding: