

Most soy sauce contains gluten and almost everything contains soy sauce. So, it’s actually somewhat difficult if that tiny amount causes issues. The good news, though, is that food labeling laws are pretty good for stuff you buy yourself, so looking for 小麦 on labels to avoid them works. A lot of people do struggle, though. Most of the Japan-focused subreddits never moved over here, but they do contain threads about the topic as well if you search.
I would note that vacationing somewhere and living there are two different things. I came to Japan a few times before moving here (and failed my first time at living here due to visa issues). Even after moving, there’s a honeymoon period and things eventually just become normal. In other words, there are two things to keep in mind: don’t over-hype anywhere and build it up too much in your head or you’re asking for trouble and any problems you that aren’t physically confined to your home will follow you eventually so be sure to work on that separately.
That said, it’s certainly possible to move across the world. Break any goal down into achievable chunks of individual items that need to be done and track progress against that. Good luck!