Apparently OIDC for the web UI is in the pipeline, so your OIDC IP (e.g., Authentik) could provide and/or enforce this. I’m not aware of plans to incorporate this into TrueNAS itself.
Edit: see also:
Edit 2: Notwithstanding what Kris said above, it appears that oAuth will not be integrated into TrueNAS, but rather will only be incorporated into the subscription-only TrueNAS Connect.