Home Assistant + plugins/extensions ~might be the easiest. Unsure about the VPN part. If you want to tinker and do some sysadmin work, then go install Proxmox and have separate containers for each as you wish.
Tailscale VPN addon for HomeAssistant is relatively simple to set up. You can use it to access your home network remotely ("site to site networking") or to proxy your network traffic through your home network when you're away ("exit node")
Yeah Tailscale is great. I assumed VPN as in tunneling the whole network external traffic through the machine. I haven't searched for something like that. Might even need a full blown router service/VM.
