In my opinion, the collected by Itch is the easiest approach. In that case Itch.io takes care of taxes related to sales, and you only need to worry about the money you earn.
I seem to remember one form about the tax interview being optional and when not completed Itch collects the default 30% rate. I might misremember as it’s been a while since I went through the process. The comment below contains a lot of useful information.
iv never had any relation to the US in all my life
At the end of the day Itch.io is based in the US. The forms might look intimidating to some at first, but you only need to complete them once.
Hope that helps! Making a game is already quite a big and complex task, hopefully setting up all the tax documents is not as big of a task!