I have used the Knollary PubSubClient with Arduino successfully. I have used it via the Tasmota project with the Arduino IDE to control pumps with flow control (also using Node RED). The reason I would prefer a uLISP implementation is having a high level language like uLISP would let me write the application logic in a more reliable, consistent manner. C / C++ is not good for this especially if you are not looking at the same codebase regularly. Tasmota covers all the easystuff, but makes complex logic almost impossible. If someone has the skill to make a uLISP pubsub extension, I would be prepared to raise money to fund it. I understand from what I have read, that for a skilled person using the FFI interface, it is not only possible, but relatively straightforward.
