So, I know at least some species of hoof snails can move (and some of them do so slightly even while on their host over time), so there's a good chance it'll move on its own to a new host. That said, if it doesn't, reading up a little on what they eat, it seems they may eat snail mucus, mantle tissue, and feces; microalgae on their host's shell; detritus; and coralline algae. So, I'd personally try offering them small sinking pellets (I'd recommend Otohime pellets and NLS pellets - the Otohime brand is higher is protein while the NLS pellets contain a good variety of algae), though you may need to isolate the snail for it to get them/not be outcompeted for the food by the other inhabitants of the tank.
There's no guarantee it'll take these feeds, but it seems to me like it would a good place to start trying at least.
*Sources:
https://academic.oup.com/mollus/article/79/1/1/1027456https://inverts.wallawalla.edu/Moll...by extending,of detritus and coralline algae.