Delta configs are not supported by victron, so i personally would not keep selling systems for delta grid setups.
A possible solution could be to recalculate the measured values to match 230/400V wye and sending that through a virtual grid device in nodered.
So for example, the the measured phase voltage between L1 and L2 (which are connected to the MPs L and N input) could be passed straight to the virtual device as the L1 voltage. Thats the easy part.
The complicated part is the power, since the power meter calculates the power out of L1 voltage, L1 current and L1 power factor. But since in a delta config, loads will be connected from L1 to either L2 or L3, the L1 current is a compound value. Further, the loads will very likely be unbalanced, so a simple squareroot of three is not enough.
Which should give you the equivalent current for L1 in a wye config if i didnt make a mistake.
Together with the equivalent wye voltage you could now calculate the VAs for each phase and pass that on to the virtual grid device. This however does not take into consideration the power factor, which if im honest, goes over my head currently. Im fairly confident you can do it the same way as you would for the current, but im not certain. Also, all of the resulting wye equivalents would only be useable for ESS, for example to regulate to a net zero import/export. They would not work as a way for the customer to know how much power is consumed on L1 for example