Video game library manager with support for wide range of 3rd party libraries and game emulation support, providing one unified interface for your games.
Support for custom metadata providers was added in Playnite 6. You should be able to create custom plugin for this now, without any addition support from Playnite required.
I think this should be offered side by side with the IGDB support. https://github.com/orels1/rawger or rawgpy could be used in grabbing that data