We already managed to impersonate non-Grief objects with strings last update...So that seems extremely likely.
Illusions that aren't just grief masquerading as said object though...
I think we want to examine a live familiar before we try and replicate one, if only for a better idea of just how it works.
The Witch thing runs into a problem- we don't know yet just how that familiar-grown Grief Seeds forms. A good starting point there is seeing if familiars that eat grief marbles form Witches with Seeds or not.
Hammer infusion doesn't work, and I'm not sure where we'd even start for teleportation.