G'MIC is an optional dependency of media-gfx/darktable. For now the relevant USE flag is masked on arm64 but it would be nice to have feature parity between arches, assuming it works of course.
Sanity check failed: > media-gfx/gmic-2.9.2 > depend ~arm64 stable profile default/linux/arm64/17.0 (9 total) > media-gfx/digikam > rdepend ~arm64 stable profile default/linux/arm64/17.0 (9 total) > media-gfx/digikam
~arm64 added, closing