I don’t think there are any Nengo examples (any maintained by the Nengo dev team) that explicitly use a continuous action space. There is one example that comes close to this though. This NengoFPGA RL example has an agent that uses discrete actions (go forward, go left, go right), but these actions are combined as a weighted sum, so the agent operates with a effectively continuous action space.
Note that the NengoFPGA example does contain some FPGA specific code, but it can be converted back to “regular” Nengo code quite easily. See this documentation for an explanation.