VMware is a different beast altogether. Maybe it'd remove the maintenance of a physical NT machine, but you'd still be maintaining the whole NT software system, and honestly that's most of the headache. Plus the overhead VMs have and all.

Containers run on your kernel and hardware natively, with a tiny bit of shims from the kernel side so it's a different root and possibly removing raw hardware access. Oracle 8i should run just as well as it would have 20 years ago, if you have all the userland libraries in order (hence putting an old distro in the container).

As long as Oracle isn't internet-facing (you can setup the container's networking however you wish, with whatever firewall rules you wish), it should be fairly safe. The modern kernel you run it on should be up to speed on the latest security patches too.