At least what Google AI said right now is that Germany allows dual citizenship, but that this is relatively recent. The US also allows dual citizenship, and has for a while.
One issue for US citizens working abroad is that US tax code is very complex for someone who has US citizenship and lives and works outside of the USA. It seems to be tolerable if your taxes are sufficiently simple (which they might be at least while doing a coop as a university student).
For most of your list this is likely to result in way, way, way too much debt. You do not want to go that far into debt. Any debt at all will constrain your future to some extent, and if you need to take any debt you should keep the total amount as small as possible.
This might depend upon whether you can find an affordable option in the USA. We did not find anything in the US that would be even close to $25,000 per year without need based aid except for our in-state public university with merit aid. If you can get in-state status in Maine it might be a reasonable option. I am wondering what U.Mass Amherst would cost since it has a very good math and computer science programs and also has some possibility of merit aid for out of state students. However, it is not clear to me whether a 3.8 GPA would get you merit aid, or maybe (?) even admissions out of state for either math or CS. I also do not know whether they have business informatics.
I do not know whether employers in the US have heard of the university that you are considering in Germany. However, they have definitely heard of IBM. The coop program with IBM to me sounds like a great option. Learning on-the-job practical skills in my opinion may improve the amount of practical knowledge that you are likely to pick up from the academic part of your education.
I would personally be a bit surprised if Michigan or UIUC turned out to be affordable. Ditto for Bowdoin, U.Penn, Colby, Bates, and Amherst College. You do not want to take out a huge amounts of loans. It might be worth running the NPCs.
I would not apply ED or ED2 anywhere without first running the NPC.
I am also wondering whether a bachelor’s degree in Germany plus a one-year master’s degree in the US might cost less than just a bachelor’s degree in the USA. One daughter, with dual citizenship, did get a bachelor’s outside the US (but in Canada) and is currently getting a graduate degree at a very good university in the USA (but not a masters, instead a PhD in a biomedical field). I also know multiple other people who got bachelor’s degrees outside the US and then got some form of graduate degree in the US (master’s, PhD, or both). This includes some who got their graduate degree(s) at some highly ranked and well known universities in the US.