Hmm, while one can use the PVE acme integration for such a thing, it may really be nicer to automate the setup for the VMs (with ansible or something similar) and use acme.sh directly in their, once setup it's all automatically anyway.. I mean, once can have a lot of VMs/CTs per node, and it's really not designed for this. Also ACME has various rate limiting knobs they enforce, e.g., 50 new certs ordered over the same IP per week, one would need to use SAN (subject alternative names) to be efficient enough for such a case...
I mean, some improvements to efficiency are planed anyway, but not sure if/how we can open this up for 10s to 100s of certificates per node..