Forge accessing confluence product fields

Hi, we are currently looking into developing an app that would be located below the navigation bar across the entire instance, we found an app that seems to access the same location. We are unsure if this app was developed with forge or connect. We would like to do this with forge but we haven’t been able to find any documentation for how to do this. Is this possible and is so, how? And if this was done with connect, again, how?