https://csrc.nist.gov/CSRC/media/projects/cryptographic-module-validation-program/documents/security-policies/140sp3678.pdf describes what's needed to make a FIPS certified build of boringSSL. Be warned that this is some ancient version and you'll have to play games with the toolchain.