Hmmm pin3 as in Snd or /WE? (depends which end you count from)
In either case, it can be supported. My BennVenn carts operate with Flash WE tied to cart-bus WE. If that is the case then two birds with one stone.
I'll be detecting cart types via the Flash IC's CFI information. This will allow almost complete compatibility with any cart (assuming there is no /WE trickery or boot sectors need unlocking [nanoloop] in which case firmware updates will be necessary)
I'll post updates soon