But a discussion about impossible things is pretty pointless ...
You can't use a NAV3/4-NC on a NAV2 device and you can't use a NAV4-map not even with known meta-Code on a NAV2-device. And certainly not a Go-app map. Only NAV3-maps with known code are possible. These things are a fact, no speculation.
By the way: There was nothing to "crack" in the Go-app maps (these always for free), "only" the usage restriction in the Go-app had to be canceled out.