If you want up to four possible input positions on each box, one system would be to wire up as you have at the moment, but use the existing female Wago ports only as outlets. Fit a snap-in male inlet at each corner but wire all four separately to a selector switch, from which the output feeds into the existing wiring. There are strict technical requirements for the type of switches that may be used, to avoid the unused inlets becoming live in the event of switch malfunction. The switch would likely be fairly expensive. The input selection could be made automatic using relays, again with technical requirements to prevent unused inlets becomeing live.
You could avoid the selector switch by an alternative scheme of wiring, with a disadvantage of many extra connectors in a chain and with them the increased risk of the safety earth connection being broken somewhere along the chain. The idea would be to wire each corner of each box as a separate, identical unit with parallel-connected male snap-in inlet, female snap-in outlet, appliance outlets and a cable to the next corner where it terminates in a cable-mounted female. Normally, the cable-females would be plugged into the snap-in males, to make a complete ring. To power the box, the female cable connector would be disconnected from the snap-in inlet and the supply cable attached instead, from which all corners of the box are then powered by the (now broken) ring. The jumper cable to the next box can be taken from any corner as all snap-in females are now powered.
I think the number of connectors in this confguration is a genuine concern and would not really recommend it. With four boxes plugged in the least favourable layout, there could be 19 pluggable connectors between the main supply cable and the last appliance outlet.
