Note to future players: Be careful about the mine cart switches! If you press a certain pair in the wrong order you will be soft locked! Be sure to save before each dungeon!
That aside, this is a pretty complete RPG experience. I am impressed.
The gung-ho system helps trivialize most battles and having the best gear further ensures you'll take little to no damage most battles, but I also recognize that I fought most battles and if it weren't for this the battles would have been a SLOG. So I guess it balances out.
Speaking of slogs, having to backtrack through the whole dungeon after defeating the boss was not great. Consider adding some sort of teleport to start mechanic in the future.
It's also cool that there are some secrets if you're willing to look. I didn't have the time to explore fully, but I like that the effort was made.
The maps look good. They are a little on the large side, but nothing too boring or easily lost in. There's a fair bit of detail packed into each area. I like that you figured out how to get an overhead path to work.
I love how the on-map sprites emote, and the battle particle effects look beautiful.
I hope you keep at it with game dev, because you have some good stuff going on here.