Change colors at runtime


I want to enable the user of my app to completely choose the colng of it, store the choice in the options, save them to and load them from storage.

So far this works when I load the settings at startup to a property of a class all pages derive from.
Most components can just bind to that. Problems come up e.g. with the ion-datetime, which has ok-, cancel-button, and currently selected values shown in the primary color.

I can not use sass/css since I can’t apply the user choice at runtime.
Is there any other way than writing my own ion-datetime or derive the existing?