There is a Demand PCB (EKRP1AHTA) which has 4 digital inputs which expands the single power limitation to 4 different levels of power limitation depending which of the 4 digital inputs is toggled. It would require a little bit of external control to make it work but would do what you want. I wonder whether one of the inputs could be tied to the 3 way valve switching to DHW for example. Its detailed in section section 6.6.2 of the installers manual.
There’s also the Smart Grid module which is intended to be connected to an electricity meter to match heat pump input with solar production, this could also be manipulated to do what you want. Again still needing some external control. Section 9.2.14 of the installers manual for this one.
I can see the issue with substantially limiting input power being an issue during defrosts. This will also apply during DHW production won’t it?