I knocked together an RGB-to-component converter for my Apple IIGS a few years ago, but compatibility with TVs has been a bit hit-or-miss as it seems more than a few don't handle 240p video well, or at all (as opposed to 480i, which they all handle). These same TVs often work just fine (if in monochrome) if I run a cable from the Y output of my converter to the composite input, which suggests that 240p over composite is acceptable.
I have a hunch that many of these would accept 240p over S-video. S-video should be nearly as sharp as component, with maybe just a bit of color inaccuracy that you might not even notice. I also have a hunch that an off-the-shelf S-video-to-HDMI converter is more likely to work with 240p input than an off-the-shelf component-to-HDMI converter. (I have one of the latter. It didn't work. Fortunately, it was cheap.)
This is a first stab at converting Apple IIGS RGB to S-video.
The models I could find for the component output connector had the pins off to the side. The CUI RCJ-32256 I've used in the past and the "Won Hung Lo" equivalents I have on order have the pins centered on each connector. I ended up taking the model for a single-jack part from CUI and cloned it in FreeCAD to get three of them, 15 mm apart. Apply color to match the Won Hung Lo connector (it has Y and Cb swapped vs. the order on the CUI connector), export it to .wrl, pull it into pcbnew, rotate and align it, and call it a day.
Found a model for the S-video connector, added it to the render...and look at how it turned out! This 3D rendering thing is turning out to be useful for finding mistakes. Still not sending the board out to be made until the parts arrive, though.
It did surprisingly well with a small set of low-resolution photos provided as an example. It'd be interesting to put a part on a lazy susan, spin it in front of a DSLR, and see what kind of models that method can produce.
I have most of the parts on order with various AliExpress vendors, so it's going to be a while before they arrive so I can verify that all of the footprints are correct. I think I'll also need to shuffle the component outputs around a bit, as the connector I have on order is arranged Y-Cb-Cr, while the connector I used previously is arranged Cr-Y-Cb.
Some components are missing from the component-side render because I don't have models for them to use with KiCad. It's mostly the connectors that are missing, though the Sony CXA2075 (the chip that handles the conversion to S-video and composite) is also not rendered.