This is exactly what Kanidm does, and there is already some ideas around application password validation via the LDAP facade.
16 karma · joined October 16, 2021
As mentioned, the main goal is "all in one" to avoid the FreeIPA style fragility from using lots of moving pieces. Making everything tight knit gives us a lot of ability to change and adapt to what we need, rather than being bound by what other projects want to do :)