Cdifan explains the CD-i widescreen issue: "On CD-i, "wide screen" means "able to drive the 16x9 signal on the SCART (euroconnector) output". This signal causes widescreen TV's to switch into 16x9 display mode, stretching the incoming 4x3 signal horizontally so that it fills the entire screen. The actual video signal never changes, it remains 768x560 interlaced (PAL); due to restrictions on color resolution and vertical filtering this is really just 384x280 with some resolution enhancement in horizontal and vertical direction. It's no better then plugging a CD-i into a modern TV and using the stretch feature to stretch "full screen". But note that the SCART connector provides (analog) component video so it's a better quality then just composite video!"
Interesting detail is that Retrostuff remarked that the option on his CD-i 490 actually doesn't work at all. But it seems that certain models of the CD-i 470 and CD-i 490 still have the option to output widescreen video format (16:9 aspect ratio). Retrostuff: "No, they only have it because Philips forgot to remove it from some of the system ROMs - it doesn't work. But all players with SCART output have this function. I explained it when I upgraded my 490 with a SCART output: https://retrostuff.org/.../philips-cdi490-rgb-scart.../"
[Thanks, cdifan, Retrostuff, Muh Mullet, Jeroen Iking, picture by Ricky Miller]