I really don't see the point, cross-platform software with multiple binaries is absolutely fine. I've shipped cross-platform software and it's a one time trivial cost to prepare a multi OS pipeline. The actual problems come from dependencies and I'm sure you'll have to solve the same problems with cosmopolitan.
Llamafile is another hack I'd never use - why limit myself to the models supported by llamafile when I can just install llama.cpp? (the web interface is also part of llama.cpp https://github.com/ggerganov/llama.cpp/pull/1998)
Moreover, people with GPUs will likely want to use something with better performance than llama.cpp (gptq or exllama2)