I have wired up CI/CD of my on-premises Git server with Azure DevOps Pipelines using self-hosted agent.
Can I utilize Azure DevOps - Boards for end to end to WorkItem tracking or is it not possible when using on-premises Git?
Is not possible. Azure DevOps can link to work items only commits from Azure Repos or from GitHub and not from an external on-premise Git server.
(to Jira have a tool that connect commtis from any git server, but I don't know about a tool for Azure DevOps).