If your functions are "stateless" (by which I assume you mean they don't depend on or modify outside state), then they are pure functions so... that's exactly FP?
That’s my point. FP can be as simple as that, and applied to any codebase. It’s all the extra stuff (which is good) that typically “defines” FP that scares people away, and keeps them from seeing the utility of a simple, pure function.