The single seater Sukhoi Su-57 wasn't originally started as a joint Russian-Indian project. That is bollocks. The Su-57 came out of the PAK FA Russian Air Force project and its T-50 series of prototypes. It never had any Indian funding. There was supposed to be a special variant of it for India. A dual seater aircraft project codename PAK FGFA. India was supposed to contribute money and software to that project. India made a small initial investment but then pulled out of it claiming the Russian technological base to make the aircraft wasn't mature enough and they didn't have enough workshare.
Anyway, the Indians only saw the initial version of the T-50 prototypes. Back when the AESA radar wasn't yet fully developed and it used a Su-35 cockpit and avionics. This was made because the initial prototype was meant to test the airframe and the flight control laws. Not the electronics. Since then it has got the AESA radar, more modern cockpit, and latest generation Russian avionics. Which are like a decade and a half more advanced than those in the Su-35.
And the Russians seemingly will develop a dual seater on their own anyway. They already published a patent on the airframe design.