Content in a Plone site can be searched for by invoking the /@search endpoint on any context:
GET /plone/@search HTTP/1.1 Accept: application/json
A search is contextual by default, i.e. it is bound to a specific context (a collection in HTTP REST terms) and searches within that collection and any sub-collections
Yes, but using the 'path' requires me to 'remove the domain name' from the string and then use this. Sounds like an extra operation that should not be needed since we have th UID (?) . plone.api can search within an item/UID, so I thought it was possible here too ? To me, it sounds like a very common task, so it is a bit strange if it is not possible
No, plone.api.content.find() accepts a context to limit the search. You can get the context using plone.api.content.get() and then use this for your search. So the behavior is consistent between plone.api and plone.restapi.
Slightly off topic: I wonder if it is possible to find the modified date for a certain object. (then I will only search(list) if the folder or its content has been modified)
I assume I could do (but it feels a bit complicated for 'such a simple task')
This will get you all items modified after 18th of April 2021.
So in your example your first query for the folderish content can already contain the modified query, then there is no need to parse and compare data in your app.