Pemmican came up in Saturday's post about the classic Abercrombie and Fitch catalog. Despite it being a mainstay of emergency rations well into the 1980s there didn't seem to be a single company offering it today. There are some "pemmican bars" that mix meat with dried fruit, but they're missing the tallow or suet characteristic of classic-era pemmican.
I spent about twenty minutes Googling the subject on Saturday and wrote it off as a product with too little demand to justify production. Imagine my surprise when I ran the exact same search today and discovered completely new results. US Wellness Meats is producing genuine pemmican made from beef, tallow, and dried fruit for the keto market. According to their company blog it's available in both bars and tubs. The tub looks like it would be perfect for recreating period pemmican rations. According to the blog keto users use the bulk material to form up their own pemmican bars, which is exactly what you want for making Antarctic expedition rations.
I can't attest to how palatable the product is, but I did order a few bars to give it a try. This wanders into true geek territory, but it looks like you could put together a pretty accurate expedition ration pack with off-the-shelf products and some custom labels.
Update: So much for that idea. The pemmican is a frozen product and there's a minimum order of $75. That's a bit beyond my experimentation budget.