Bitcoin is not natively programmable like Ethereum, but it is still possible to create non-fungible tokens (NFTs) on top of the Bitcoin blockchain using a process called "colored coins." Colored coins are a way of attaching metadata to a bitcoin transaction, essentially "marking" it as representing ownership of a particular asset. This can be used to represent NFTs or other types of digital assets, although it is less flexible and more difficult to work with than the smart-contract functionality on Ethereum. So, while Bitcoin is not natively programmable, it is still possible to create NFTs on top of the Bitcoin blockchain using colored coins.