I'd say "WASM-powered serverless functions" is a reasonable analogy, if your serverless functions maintained a minimal number of live replicas at any one point Also, of course, you're tied to the physical ceiling of the explicit hosts that are underpinning your cluster (N machines which are not dynamic like, say, lambdas are when they auto-provision to match demand).
And yeah, you can also `pln serve` arbitrary services which are then exposed to the cluster, but it's worth mentioning that these will of course not benefit from the inherent, organic autoscaling and locality mechanisms that come with the WASM blobs. I only added it in as a feature so I could retire my (basic) Tailscale usage.
Also, you can `pln seed` arbitrary blobs which can be `pln fetch`ed from other nodes. You can also `pln seed ./public my-site` a static webpage which you can reach from any node with `curl -H "Host: my-site" http://<node-addr>:8080/` (8080 being a configurable port).