I have a workspace with 2 databases shared with my integration, basically it works and I get 200 OK code.
That's the function I have, the headers contain the authentication token:
def listDatabases(self):
r = requests.get('https://api.notion.com/v1/databases', headers=self.headers)
if r.status_code == 200:
return r.json()
else:
return r.reason
And this is the result: