Some airlines hire OCI's... some don't. Best to contact individual airlines. Policies changing on a daily basis. No direction from the DGCA on this topic...so far. And the expat FO issue does not affect PIO\OCI holders.
I would reckon that that with plenty of Indian citizens waiting in the wings no reason to hire OCI's\PIO's. However, with OCI's being hired on local terms airlines don't care who fills the seats.
As far as I know, AI, IC, 9W do not hire non citizens for the right seat. As for all other ailines, as I said, give 'em a call. Good luck.