FunLess is a Function-as-a-Service (FaaS) platform tailored for private edge cloud systems. FunLess leverages WebAssembly as its runtime environment for performance, function isolation, and support for heterogeneous devices, crucial for extending the coverage of serverless computing to private edge cloud systems. We benchmark FunLess against three production-ready, widely adopted open-source FaaS platforms-OpenFaaS, Fission, and Knative-under different deployment scenarios, characterised by the presence/absence of constrained-resource devices (Raspberry Pi 3B+) and the (in)accessibility of container orchestration technologies-Kubernetes. Our results confirm that FunLess is a suitable solution for FaaS private edge cloud systems since it achieves performance comparable to the considered FaaS alternatives while it is the only fully-deployable alternative on constrained-resource devices.