As of 4.3rc1, this is (*technically?) possible! It took some stumbling, plus I’ve written my own script to manage domU-based window-borders + workspaces, and compiled a relocatable software profile from source which (ugh!) segfaults on resume-from-suspend >u<
Baseline Niri is very close to shippable though, and IMO within reach of determined users, though running popular Quickshell configs that depend on Qt6 requires more experience and is not stable :c
I’ve put short clips of two such shells, DankMaterialShell and Noctalia, up on my fedi, which I don’t see any rule against sharing – think I’ve earned that: