Current requirements:
OCSP responders operated by the CA SHALL support the HTTP GET method, as described in RFC 6960 and/or RFC 5019. The CA MAY process the Nonce extension (1.3.6.1.5.5.7.48.1.2) in accordance with RFC 8954.
RFC 6960 supports different hashes.
RFC 5019 requires SHA1.
In anticipation of https://datatracker.ietf.org/doc/draft-ietf-lamps-rfc5019bis/ getting published please consider starting a ballot to require SHA256 to be used instead of SHA1.