I was really into Hetalia in my late teens, but I never actually properly sat down to read the manga. I have now done that, and I honestly don't think it's the best format for this series. You can tell it was originally published as a webcomic; it's very episodic and doesn't really tell a coherent story, especially as strips aren't necessarily presented in chronological order. I would probably just reccomend watching the anime and looking at Himaruya's blog tbh.