It’s the “without resupply” part that is tricky. Any Moon or Mars colony would be able to mine resources, either using stuff on the Moon or Mars, or asteroid mining. Plus, we could still supply them with things they can’t make yet, like computer chips, even if it would cost a lot.
A better comparison would be the Generation Ship stuff we discussed a while ago. We could design something that would last a long time using stockpiled materials and replacement equipment, but the real question is “how long”?
And we can quibble about that being “self” sustaining. They survive because of a massive investment by the technological society that sent them off. When that investment runs out, they’re screwed if they haven’t built something self-sustaining at a new home.
And a Generation Ship would have a choice about where to put the new colony to maximize the chance of success. Place it near useful resources, like a forest, and the local equivalent of coal and oil deposits, and a lot of the biggest problems become much more tractable.
Antarctica is one of the most inhospitable places on our planet. Virtually no native plant life, limited wildlife, and difficult access to pretty much every other resource. That makes a self sustaining colony far harder.