I'm aware CE no longer supports KV stores for LE/ACME Certs, but is there a way to disable renewals on some nodes and use other shared storage methods (such as shared acme.json volume via portworx)?
Current workaround is to start one container, wait a day and then start the others, but if I can control which one does the LE Issuance, either by manual external cron-job or an api hook, that would also work for free-tier?
You are correct that CE no longer supports multi-node acme certificate (LE) management.
If you use an external tool (such as cert-manager, lego client, certbot, or other tool) to manage the renewals, then the certificates can be used with Traefik, just as self-signed certificates would be.
That way, you could use your external tool to manage renewals, and allow your Traefik instances to mount and use the certificates, and not handle renewal.