Solution
There is no direct equivalent for the "AI Single Scan.vi" and "AO Single Update.vi". Instead, DAQmx uses the "DAQmx Read" to read AI signals, and "DAQmx Write" to write data.
However, the Traditional DAQ functions are available if both Traditional DAQ and DAQmx are installed.
National Instruments recommends transitioning to DAQmx entirely to minimize any problems with older Traditional DAQ functions. See
Transition from Traditional NI-DAQ (Legacy) to NI-DAQmx in LabVIEW for guidance on how to do this.