As you’ve found, proxmox isnt an application that runs on windows or Linux. It’s an OS that you can install. And yes, you can configure bit to auto start the VMs when the machine boots.
It’s designed to run headless, so you’ll do all your configurations from a web browser. If you want to go crazy, I’m sure that raspberry pi can be configured as KVM for it (though piKVM is a bit of extra hardware.)
If you have something like tailscale or wireguard to a machine in the house, you can easily reach the web gui from any other machine on the VPN network and reboot the VMs that way.
You can even build monitoring that reboots the pihole VM of it stops responding to DNS queries.