Nixos/nixpkgs: isolated dependencies / services, easy to override if needed, configs follow relatively consistent pattern (main options exposed, others can be passed as text), service files can do isolation by whitelisting paths without going full-blown self-contained-os container.
> Are you running random images from the internet on your servers?
Many home server users do this. In business use, unless you invest lots of time into this, a part of your services is still effectively a random image from the internet.
> and those from Bitnami
Yes, that's a random image from the internet.