Generally, I think it is better to use a general server OS like Debian or Fedora instead of something specialized like Proxmox or Unraid. That way you can always choose the way you want to use your server instead of being channeled into running it a specific way (especially if you ever change your mind).
Self-boting is against ToS. You have to be careful when interacting with the Discord API. Maybe there is a way to run the discord website to fetch text messages.