> In parts of Australia there are designated "reference areas" which have a higher level of environmental protection than national parks. They are typically remote areas that humans do not visit and have not historically and directly disturbed.

> I've tried to find similar for Finland. The closest I've found is [1] which maps "old forests" which are defined to be over 100 years old (not actually very old).

The history of civilization in Finland is much longer than the history of civilization in Australia. You shouldn't expect to be able to find "areas that humans have not historically disturbed" in most parts of the world. Certainly not in parts of the world that can grow trees.