Aaron Rutten put out a great video on 5.3 features. He shows how to use this new docker but I don’t see it on 5.3.1.1. This video will open at the point where he introduces it.
I found a post from 2025 in which @freyalupen says it’s a plugin, therefore not available for Android. Krita 5.3 prealpha - you can create a custom toolbox in it - for me best since sliced bread - #6 by freyalupen
If it’s built in to Krita now, could it be added to Android?
Pinging @Drawpile