My car (Enyaq) can limit the charge to 4A, that means on 230V it will make less than 1kW. But the added charge is very small - with 1kW the car adds in 5 hours of daylight only around 20km.

If memory serves me right the Spring can Charge with Up to 6,6kW Single Phase only. But the thing that Sets the current ist the EVSE aka wallbox aka Chargenrick. In the EU this can range from 6A to usualy 32A but Higher is possible. Multiplied with the voltage of 230V you get 1,4kVA (kW) to 7,4kVA (kW)

So yes technicaly it IS possible when your chargecable can Set a Current of 6A.

however some vehicles mostly known as Renault Zoe have Trouble with Low charging Rates but only with 3 Phase, Single Phase is fine 6-32A and 3phase 8-32A.

I asked a Spring owner who has a load Management System If the Car is fine with 6A. However it will be slow as a snail and the losses add up over time but it dosent Matter If the Energy is free.

IMHO i would Just Stick to the 2,3kVA 10A setting. The Overall efficency is Higher and thats important when you cant supply the 1,4kW constantly.