If you’re going to use VMs or containers when you definitely want more RAM. The CPU looks fine though for that use. If you’re using it as a media server you’ll get through 500GB in no time at all, so make sure you’ve got space for more drives.
I’ve had success using FreeNAS (now TrueNAS) for this sort of thing in the past. That’s got the Jails feature for virtualising apps. I haven’t used Unraid or proxmox so can’t compare it to those.
Jeez, I’m a bit jealous of that compared to my 1g/1g service in the UK at £260 per month! I hate to think how much a commercial router/firewall fast enough to handle those kind of speeds would be. As others have suggested, building your own and running something like pfsense or vyos is the way to go. Best of luck, you’re getting a fantastic deal there!