Once again, I'm trying to avoid having to use a DAW or a computer. If I simply want a really good recording in wav format of a Song created on MOXF, what are my options? I know the MOXF has an audio interface built-in to the synth, but not sure it's germane to what I'm trying to do.

It is not. The Audio Interface allows your MOXF to communicate with a HOST device (either a computer, laptop, or SmartDevice) via the USB connection. Using this connection and the Yamaha Steinberg USB (ASIO) Driver or connecting to a Class Compliant tablet or phone, you can deliver pristine digital audio to that device. You would use a DAW (digital audio workstation, like Cubase) or an App.

If you do not wish to use a DAW or Computer, you can record to an iPad for example (not sure if your desire to avoid computers extends to tablet devices) with an appropriate App like the Yamaha Cloud Audio Recorder (for iPad)*.
Recommend you use the USB Connection rather than the built-in mic on your iOS device... much better quality with direct USB connection.

*we have to note, this App may not be available in all parts of the world, please check.

You're other options include a myriad of hand-held recording devices that can take audio directly from your MOXF's Main L/R Output.

Also we should mention about recording, there is nothing "simply" about getting "a really good recording" - it takes practice and skill, but we know what you mean. You will be amazed at how good a recording you can get with today's hand-held recorders - next time you in your local music store, check them out.

A .wav is a computer format - compatible with a lot of devices. Setting up Cubase will allow you to create a Stereo .wav file - if you decide to stop avoiding the use of a DAW/computer.