The 4in1 cart bundled with the GS is 512K, also Myth and Last Ninja Remix released by System3 were 512K also. Amazing what the GS console is worth today.
As for a Briley cart, it could just about work with old tech if you cannibalised an old GS 512K cart and replaced the bank switch chip to handle 2MB afaik. You’d have to save to disk though. Only the more recent carts allow you to save back directly to the cart itself.