Mojo code can be built into a static or dynamic library, those are really just different options in the LLVM backend, however, interfacing with it is hard. Mojo doesn’t really offer guarantees on what is C ABI compatible. This is a lot of stuff which happens to work, but that could change at any time.
IOS support is probably very, very far into the backlog. Windows is likely higher priority, as is AMD GPU support and probably a few other major vendors like Intel GPUs and Apple’s Metal API. IOS is a fairly closed ecosystem, so getting a new language to be able to support it is difficult. Mojo itself has many, many features which break the “no jit compilers” rule, to the point that I’m not actually sure if the full Mojo language would be allowed on IOS.
Better C interop will come, since Modular needs it for their C API for MAX, but it might be a bit.