Dallas here from the Shopify Social Care Team.
To be honest, I would need some more information about what you mean about your business entity is in the USA. Does that mean you have an office over there with employees?
For something like this, it can be a tricky situation. I'm not able to give official information because a situation like this will have a large number of variants that need to be taken into consideration when it comes to figuring out where the legal bases of your business is situated.
I can say, however, that I strongly suggest you focus on where you're business is operating from rather than where you're selling to. If you're using Shopify payments you're going to want to make sure that you have all the supporting documents for where you resided and where you operate from. Based on what I am hearing it sounds like most of that is in Germany. In that case, I suggest that you centralize your business location to Germany rather than the USA. This would help to avoid payment provider questions that might arise in the future if you were to go with the alternative of putting the USA as the address since you don't have proof of residency for that country.
This can be a tricky and confusing topic so I do suggest that you reach out to a local legal professional who will be able to provide more information on this topic for your specific situation.
If you have any other questions, however, please don't hesitate to ask.
So for that, you're going to really want to make sure that your Shopify store is in alignment with where you're personally located. If you set the location as the US, but you're constantly working on it from Germany then that could make it as some suspicious activity and then there might be extra steps of authentication and verification.
Although I can't provide legal advice, it's generally recommended to have an LLC to operate a business in the USA from a different country. I recommend seeking legal counsel to fully advise you on the requirements for both countries and any forms you need to submit to those governments.
I know this is a short message without a lot of extra information, but the biggest thing I can re-iterate is that you should really speak with a legal professional on this.