I go through different switchers to various inputs of the retrotink4k. I avoid composite to keep it simple and get a better picture.

• Dreamcast -> VGA
• PS2 -> Component Switcher
• N64 -> Component Switcher
• GC -> HDMI GcVideo adapter (forcing 480p through swiss) -> HDMI Switch
• Nintendo Switch -> HDMI Switch

Wobbling Pixels put together a good comparison between CE, Morph, and OSSC Pro. According to that sheet dealing with sync, the OSSC has issues with switching resolutions if the aspect ratio is set to 1:1 instead of something like 4:3

If it makes you feel any better you’re older than the parents from Rugrats too.