SaaS and Special hashing function

Dear community, we use a special argon2-based hashing function for our customer logins.
Could we migrate to Keycloak by providing the hashing algorithm implementation (in any language you prefer) and the database?
Could we serve as a federated auth provider to enable Keycloak as a service?
(I do get your right, correct? - it is not only a software but an SaaS?)