How do taxes work for LLCs under SOFA?

I am curious to know because for active duty military members stationed overseas, would they have to pay taxes to the country they are in such as Japan, Germany, etc.? Or will they only have to pay taxes to the US on that since it is US-sourced income? Or does it depend on the SOFA agreement?

I am curious to know this because I'm in the process of joining the Navy and I am curious to how this would work out in case if I want side income from making and selling software. So I wonder how US-sourced business income is treated under SOFA. I'd appreciate any source or tips anyone may know! 🙂