I like trying to find quirky cars in the US. A few years ago I found an AZ-1 at Heavy Seas in Maryland. Super cool car, and the owner was 6’4”. It wasn’t his daily but he did say he drove it on several trips to North Carolina.
He said they were all terrifying haha.
For maintenance parts like oil filters and belts you can usually find a local equivalent.
For performance parts I’ve ordered from both blackhawkjapan and rhdjapan in the past, they are good 👍
For OEM I’ve ordered some stuff from Yahoo auction using jauce or even with Amazon Japan.
Tires though, that’s a pita. I couldn’t find anything in OEM size (165/55r15) except from a special order of nankang branded tires. I went with 195/45r15 instead. They are tight but they fit. I’d check local to you if someone can order tires from overseas, that could help a lot.