https://www.alternatehistory.com/fo...ian-equivalent-for-the-southern-ocean.443002/ - Thread I did on maritime Fuegians
https://www.alternatehistory.com/fo...ces-of-permanent-antarctic-settlement.444062/ - More discussion on potential indigenous people of the Antarctic
Overall, they certainly could survive in those places, the problem is getting them there, since the seas are very rough and their boat-building skills IOTL weren't quite up to the challenge (even the Falklands would be a huge challenge).
What happens when Europeans find them? Basically they all die, like the Tasmanian Aboriginals and the OTL Fuegians. The women are kidnapped and raped by sealers and whalers, while the men are killed in fights with them. Disease outbreaks repeatedly decimate their numbers. Their food is stolen from them, and they end up starving. Some missionaries might come by and with the help of a Great Power like Britain, they might be resettled in some mission settlement, where they live out the remainder of their days as a decimated population which is slowly declining into extinction.
Could those Furious Fifties draw a ship out, shipwrecking some Fuegians on South Georgia?
They certainly could. It's probably the hardest part of getting the Fuegians to settle Antarctica. You also need not just male fishermen/hunters, but some women too. And of course some Fuegian dogs, which were vital to Fuegian survival. Another challenge is innovating boat building--you need to get some trees to the Falklands, and then get the trees to South Georgia. I'd expect once the trees got to South Georgia, they'd be protected by windbreaks and such, allowing for more firewood and some wood for boat building.
Maybe just summer hunting camps?
Some hardcore shamanic initiation rites involving antarctica, tying religion to the process would be badass
Once you arrive in Antarctica, you almost certainly can't return. The sea ice is seasonal (and crossing in winter dangerous due to the short days). But a Fuegian population which island hopped to the Falklands (hopefully innovating better boats and fishing/sealing/whaling techniques) and from there to South Georgia and the South Sandwich Islands would have evolved the cultural package to survive in Antarctica (and the genetics as well via natural selection--the Inuits have some genetic traits which are very helpful for surviving in the Arctic wilderness, although have led to numerous problems in modern society). From the South Sandwich Islands, they just need to go against the current and cross the sea ice to the next island chain, and eventually they'd hopefully cross the sea ice to Antarctica proper.
