Is Shinto "Kami" similar to Native American "Medicine" ?

A Native American looking at Mt. Fujiyama might say, "sacred place,heap
big medicine."
A Shintoist, "holy mountain powerful Kami."
Am I at least in the ballpark on this one?

Not really. Kami are spirits and/or gods in Shinto.

The Kami are the nature spirits of Japan. Amerindian shaman isms also usually had a stung sense of the presence and activity of nature spirits.

Yes you are on the right track.

Places contain high energy. The mountain you mentioned, Mount Shasta, and places where magi ck has been performed for thousands of years like sacred circles, Stonehenge, Silbury Hill, etc have high energy. This energy has been called by dozens of names over the eons. Here are some of the better names. Chi, italic, Ki, Marna, monitor, Kuwait, Parana, etc.

When you do magi ck in these sacred sites; your magi ck is more effective because in these places; you get the attention of the higher powers faster than you might do a working in a place that magick has not been done ever, or in a very long time.