In general, homeschooling is not allowed in Germany for German citizens and residents. However, if you are here with the US government as either military or civilian and have SOFA status, you absolutely CAN homeschool.
Homeschooling is popular in the American military community so wherever there is a base, there is probably a homeschool community. There are two active Facebook Groups in the Wiesbaden area: WATCH (Christian) and Wiesbaden Area Homeschoolers (secular).
Also, if you have SOFA status, be sure to join the Facebook Groups for SOFA-Status Americans. In Wiesbaden, there is the Wiesbaden Welcome Wagon and Official Americans in Wiesbaden. Americans Living in Germany is a great and active Facebook Group, but it is primarily for non-SOFA status Americans so it is not the best source of information because they follow different rules than we do. Ask your sponsor what the Facebook Groups are for the installation you will be attached to as Facebook is currently the best source of information. Websites are often out-of-date.
As I have said before, if you are putting non-German-speaking kids into German school, I advise you NOT to continue to homeschool in English until the German is well-established and they have friends. It is exhausting to be in a foreign-language environment and they just don’t have the capacity to do more work so you are just adding stress and slowing German-language acquisition and social integration. Your time is better spent enrolling them in a physical activity that is conducted in German that will give them more language exposure but in a less-stressful way and give them more opportunity for social connection. Social connection is key. Once a child makes a friend, the language acquisition happens faster and easier.