Good question. For us to support a particular trading venue, IBKR needs to have access to it - yes. But that’s not the only box that needs to be checked. We must establish formal relations with the exchange and the associated quote provider, to name a few others.
As far as FWB (Frankfurt Stock Exchange) goes - it’s unlikely we’ll provide access to it in the future because most instruments listed on it already have listings on Xetra, which we support.