My strong suggestion would be to avoid doing this. The compliance hoops the US will make you jump through if you are a significant US owner of a foreign corporation (the holding company) will hurt. You likely wouldn't owe any taxes, though you never know with GILTI, but you'd be spending at least 3-10k USD per year on accountancy just to file the books for the German company with the US most likely.
If you're planning on making your money in the US in any case, you might want to just set up a US holding company, or just holding the assets directly.
If you do anticipate moving to Germany any time soon, also be aware of the US expat/exit tax, which is a kind of capital gains tax that triggers when you become non-subject to US tax jurisdiction. I can't really explain it much in an HN comment.
Expat Tax: https://www.irs.gov/individuals/international-taxpayers/expa...
https://www.goldinglawyers.com/what-is-expatriation-us/
Form 5471 (one of the forms the IRS makes you file with respect to the proposed German holding company): https://www.irs.gov/forms-pubs/about-form-5471
https://www.goldinglawyers.com/form-5471-filing-rules/
Also as an aside, make sure you file FBARs (as an individual) and Form 8938 if you still have German accounts/assets that meet the criteria (they are different).
https://www.irs.gov/businesses/small-businesses-self-employe...
https://www.irs.gov/forms-pubs/about-form-8938
The US is extremely mean to people with international connections. It's very difficult to remain compliant, but as a business owner you are significantly increasing the likelihood that you will be audited, so it's best to try to keep things as compliant as you can.
Get a tax pro. Anyone who has any connections with another country will need one, just to talk to if nothing else.
Again, I'm not a lawyer or a tax pro, just a sad dual-citizen who has been screwed by US tax compliance before...