Right now, the SharePoint connection works great for simple use cases, but there are many more complicated use cases arent really working great with out of the box.
A really useful feature/maybe connector would be a SharePoint HTTP action (similar to Flow) that can use the credentials of the current user to make the HTTP Rest call to SharePoint in the context of the current user. This would ensure:
You only get the items that the user has access to
You can get around list lookup limitations of SharePoint
You can get around the delegation and large list filtering
I'd imagine your source on a form or gallery might be something like this: