Just to respond on the driving point, I have driven in both Japan and Taiwan. Japan is easy provided that you're comfortable with driving on the left - the main consideration is that speed limits are slow, but the style of driving is super polite and courteous, like the people. Taiwan is a bit more frenetic and the mopeds can come from every angle, but provided you keep your eyes open is perfectly manageable. I was able to drive into Taipei at 5pm on a Friday afternoon with no issues.

For both there is amazing scenery to discover and roadside stops and local businesses to enjoy. Just make sure you are equipped with maps on your phone to navigate in your own langage. The only gotcha beyond that I experienced were variable message signs that are typically not translated (and I can't read Japanese or Chinese) so just look it for clues in the message eg. a distance and expect the unexpected up ahead.