How should I recolor artwork on Designer?

[LCamachoDesign]

Hi! I've recently got access to an iPad Pro and I've been dabbling with Affinity Designer. Great stuff, but I've ran into limitations that break my colouring workflow. First let me explain how I do it on the desktop:

1. Draw a vector shape
2. Apply a global colour to this shape
3. Create a pixel layer inside the shape
4. Apply a Colour Overlay effect to the pixel layer
5. Attribute a global colour to the above effect
6. Draw on this layer, the pixel brush colour doesn't matter since the Overlay effect always overrides it
7. Repeat steps 3. to 6. for every colour I want to draw inside the shape
8. Move on to the next shape and start from 2. again

This way if I want to change any colour after the fact, all I have to do is edit the global colours and all parts of the illustration respond accordingly, even the pixel layers.

The iPad version of Affinity Designer does not have global colours, nor it does not support attributing swatches to layer effects... this fundamentally breaks the method of controlling colours described above... I've already requested both features on the appropriate forum, but until they get implemented I'd need an alternative method. My question is, what alternative methods of recolouring the artwork should I use? What do you use when you want to recolour the artwork after you're done?

Thanks in advance!