@hj my idea is that it’d be more like what Fedibird/etc does for custom emoji objects, but more extended; like introducing a ProfileDecoration type
so you could have, on your actor, something like:
"litepub:profileDecoration": [ "misskey:isCat", "https://p.helene.moe/objects/decorations/helene-theme.jsonld", "https://p.helene.moe/objects/decorations/post-background.jsonld" ]