Is it possible to reference the value entered by a user into, say, a text input widget, in a backend process e.g. a Python transform? I want to be able to manipulate a dataset according to user input values entered into an input widget. Really appreciate any help with this.
Yes! You can set up an action that writes whatever value the user input to a property of an object. This could either be an existing one or one that is created when the user is taking the action - whatever makes sense for your workflow. As a general rule, think of workshop as a place for users to interact with the ontology - both reading and writing - so if you want to store things they do in workshop you'll need to write to the ontology.
If you want to use it in a transform downstream you'll need to then materialise the dataset that backs this object type, which essentially captures all the ontology edits in a dataset. You can set up in ontology manager.