So this is a lot less complicated than first thought
Set up your SQL server with the correct SPNs and constrained delegation as you would do for any form of kerberos connection
The MS SQL jdbc driver can connect directly without needing any kerberos setup on the linux host or container
Username should be entered as username@REALM
The Extra Connection properties should include "integratedSecurity=true;authenticationScheme=JavaKerberos"
On a linux/container env, the username must include the realm, on windows its optional
On a windows env, the ignition service needs to be started with the same username that you use to connect to SQL, on linux the default installation can be used.