Ah, this is a helpful suggestion, and gives me a direction to point the interwebs in.
I generally use Firefox, but I also could use Chrome or Safari for this, if needed. My computer is an M1 Mac mini.
That said, after research starting from you initial suggestion, unfortunately it appears no browser will play an AAC file without it being wrapped in an MP4 container. Of course there's no problem if you download it or save it somewhere an audio app could find, but I was hoping to skip that step.
So I suppose this is one of the limitations of using the Evernote web client instead of the app version of Evernote for your particular PC type.
Thank you PinkElephant for your suggestion. If anyone else comes up with further information, please feel free to include here.