If you want this to work across ARM and x86 (or even multiple ARM vendors), you are screwed, and need to restrict yourself to using only the basic arithmetic operations and reimplement everything else yourself.

Is this problematic for WASM implementations? The WASM spec requires IEEE 754-2019 compliance with the exception of NaN bits. I guess that could be problematic if you're branching on NaN bits, or serializing, but ideally your code is mostly correct and you don't end up serializing NaN anyway.