There is a NES-RGB mod. https://etim.net.au/nesrgb/
If you want to run NES without mod, then you need something that accepts composite input, like retrotink 2x or framemeister. There is a composite transcoder planned, but no estimate when it will be released.
Also, you keep referring to Scart, you should know scart is just a connector and says nothing of the video signal.
Ossc accepts ONLY rgb & YPbPr.