No, ISRO cant design ISTAR aircraft like Raytheon Sentinel currently, but one with limited capability - yes.Ig we need the aircraft
ISTAR sensors have been developed by drdo
Infact that was what drdo proposing right it has all resources to convert an aircraft into istar
Infact in 2020 there was a report India procuring 5 istar platform 3 being completely us last 2 with drdo sensor
If wrong then sorry
A reason why IAF/GoI showing big interest in Raytheon Sentinel