We have a few PFG forms where fieldsets are show or hidden depending on the state of a checkbox. The customer's primary usecase: you select between UNSUBSCRIBE and SUBSCRIBE and depending on the selection, the related fieldset in PFG is being shows. This has been accomplished through some specific JS handlers defined on the PloneFormGen object.
The only way to implement this in a similar way would be using some Javascript code as part of the theme package...doable but not nice...any better solutions around?
There are conditions that you can use for single fields. Fields can depend on one or more clauses.
Documentation: Depends — Patterns
Still not perfect for your use case because you would have to specify this for each field separately.
There's also this section in the easyform readme: GitHub - collective/collective.easyform: Forms for Plone