Welcome.
Have you been to Japan? If you haven't visited Japan, I suggest figuring out a way in the nearer term to do so. Maybe some kind of summer language program or something like that. Even if only a few weeks. Watch for deals after COVID is gone, they will surely want to stimulate the tourism industry.
Another option that many people take is to join the
JET program after graduation. You'll need a bachelor's degree but you at least get paid to do some job in Japan for a year or two while getting an authentic Japanese experience. Not sure if you would make enough to save money though.
I would vote for getting a bachelor's degree in the U.S. first as it will give you more options to go to Japan beyond language school.
Oh, I don't think there would be much value to getting a degree in Japanese. Ability is what counts, it doesn't matter if you have a degree or not. Of course it would be helpful if you can pass the standardized Japanese ability test as it's a good standard benchmark of one's capability and good for your resume.