Hello John
Windows Server AD is not the only option to use 802.1x and password-less access. You can use various other platforms that leverage the RADIUS protocol including freeRADIUS , Cisco ISE, TACACS+, and Aruba ClearPass to name a few. These servers can integrate with various directory services, not just Active Directory.
The key is to have a server that supports EAP-TLS, which is the protocol used for certificate-based authentication in 802.1x. This allows the server to validate the client’s certificate to provide password-less access.
So, you have several options to choose from depending on your network infrastructure, budget, and specific requirements.
I hope this has been helpful!
Laz