I can imagine that theirs is safer and more suited for targeted devices. Linux is extremely generalistic and has a ton of cruft.
For targeted devices so is Gentoo. Their edge is having access to proprietary drivers.
But I have never looked at their code or tried to port a Linux app to Android. The #Krita devs might have some insight here.
If it's written in portable C you can use the Android NDK/SDK to cross-compile it for the 4 archs they support. I do it at work.
Not an actual lock-in as they (still) provide tools to cross-compile and the source is (still) available, more like a vendor push-out if you insist.