A client is requesting we come up with a Python script to have an AGOL feature layer and a SQL Server database containing similar information be able to read/write to each other without having to use ArcGIS for Server. Their concern is the amount of traffic on the in-house server and would like to bypass this. The client is also looking into ArcGIS Portal but currently doesn't have it. Also, while AGOL is clearly public, their SQL database is behind a firewall.
Doing some research, it doesn't look likely that this is possible. However, I figured I'd ask here in case anyone has tried to get around this before.
Is there any way around ArcGIS for Server I'm not finding through my own research?
[Update]: With much more clarification, I believe we have come up with a solution that would work. We know Python can interact with AGOL, and we know Python can interact with SQL Server DBs. From here, we just want the two tables to verify each other. Seems much simpler than was previously discussed.