I just forgot the TCE GUI name, as it's just a TCE frontend.
But sure I understand the TCE advantages, that's why i begin to use Tiny Core...
So APPS, alias TCE, can but does not install programs in user space (i mean like '/home'), but in rootfs (usualy in "/" root ramfs). But yes persistence allows keeping programs in user space (by squashfs or backup). Of course.
Guix is "same", but different.
To run GUIX on any distribution, you just have to install the daemon and run it.
I think TCE is perfect to deploy light packages and can offer various elegants "over mounts" strategies.
But for an as big as kodi program, it could be very hard to maintain (various architectures, run dependencies, build dependencies, compilation...)
GUIX packages theorically offer an absolute portability on any distributions.
So imagine you get your light tiny core environemment (like a swiss knife), and over it, you can deploy up to date big packages by using GUIX, then you don't have to maintain millions of TCE packages, as it's for light usage.
Last point:
You decide to update the GUIX part only? It will not affect tiny core.
You decide to update the tiny core part only? It will not affect GUIX installation.
You have two versions of tiny core using a same real home path?
Your GUIX programs could be available on each!