For your goals, I would stick with Python unless you want to learn another language. There's not much value to switch away when all the tools you need are primarily designed for Python.

As far as functional programming goes, with AI stuff, my experience is that you generally are more interested in orchestrating services than FP. For example, run input through model #1, then based on the output, run one of these other 3 models (or multiple of them in parallel), then eventually pass it all back into another service/function to aggregate and format the outputs. You can think of each of these as being "functions", but they're much higher level than what you'd traditionally consider functions in FP and more along the lines of microservices.