I’m not sure it would work. I was planning to send everything over a VGA cable, rather than SCART.
All resolutions are supported on SCART on the OSSC. In some cases using SCART in for 31khz sources can be better too (e.g Dreamcast).
I second the use of SCART when using the Dreamcast with the OSSC. It doesn’t require any additional configuration on the OSSC (DC will have the wrong aspect ratio over VGA without additional config), and I think it’s simpler to fit into any setup that already uses a SCART switch.