If you're sure you only use standard python libs it's fairly easy.

make a recipe (name it how ever you like)

SCR_URI = "file://<your script>.py"

do_install() {
install -m 0755 <your script>.py ${bindir}/<your script>.py
}

RDEPENDS:${PN} += "python3-core"

in the image

IMAGE_INSTALL += "<your recipe name>"

---

if your script needs further libraries, reference them in the recipe with

RDEPENDS:${PN} += "python3-core dependency1 dependency2 dependency3..."

Then you call the result on your device with <your script>.py from any console

Maybe add a "#!/usr/bin/env python3" shebang as a first line to your script