> Linux still doesn't have anywhere near as nice and cohesive as Group Policy, Active Directory etc.

Enterprise environments use a number of tools like Powerbroker, UCS, Centrify/Delinea etc to bind linux machines to active directory and manage identity and access through active directory. This is for mixed environments with both Windows and Linux machines.

For pure linux environments, there are a number of tools like FreeIPA/IdM, Samba AD/DC (for A/D like management), and OpenText's eDirectory for the current version of Novell's eDirectory counterpart to A/D. They all provide centralized user/host/policy/access management.

Since Entra+Intune are the recent MS products, cloud-based equivalents are Jumpcloud+Fleet, Okta PAM, FreeIPA/IdM.