Eternal rest grant unto him, O Lord,
And let perpetual light shine upon him,
May he rest in peace,
Amen.
He's just dead, mate. No resting or light; perpetual, eternal or otherwise. Same thing that happens to a fly when you hit it with a newspaper.
If any prayers are to be offered by the pious, they'd be much more appropriately dedicated to the victims and survivors of sexual abuse who suffered - and still suffer - directly due to Ratzinger and his ilk.
Have a good read of the IICSA reports and discover where any sympathies should really lie.