When migrating from the classic search experience to the modern search experience how do we handle custom indexing connectors? When using such connectors to index content from external systems, how is this content surfaced in the modern search experience?
I understand that the basis for modern search is the same search index as for classic search. So the content is there.
My focus is on SharePoint 2019 on-prem, but there is SharePoint Online on the horizon. So I'd like to have differences highlighted as well, if necessary.