There's even a somewhat-unreliable hack to create tokens on the Bitcoin blockchain, called colored coins. You create a specific transaction sending some number

There's even a somewhat-unreliable hack to create tokens on the Bitcoin blockchain, called colored coins. You create a specific transaction sending some number of Satoshis to another key, and then your coloring scheme marks that transaction as "converting" the coins to whatever token you want. The definition of the token is just anything that address spent. Of course, no Bitcoin users are required to honor the scheme, the colored coins are still valid Bitcoin and can be spent by an unaware wallet. But you can still pretend that they are, say, shares of some DAO or something. You probably could extend this to NFTs on the Bitcoin blockchain as well.