BLS signatures are general purpose, the only Ethereum specific thing is choosing which elliptic curves are used for public keys and which for signatures as well as a prefix before hashing inputs.

Similarly KZG polynomial commitments are generic, the Ethereum specific thing is the trusted setup ceremony which needs to be specialized per protocol.

The finite field backends and the elliptic curves supported are all generic as well: https://github.com/mratsim/constantine/blob/master/constanti...