Oasis Sapphire provides built-in support for secp256r1 via a precompile, however the precompile isn't directly compatible with the 7212 precompile as internally it uses DER encoded signatures and points.
The P256Verifier contract implemented in this repository provides a small
compatibility layer, translating 7212 calls to use the Sapphire secp256r1
precompile.
It is tested against the Wycheproof vectors.