I found this code to populate a select field with nav menus:
https://whiteleydesigns.com/code/dynamically-populate-acf-select-fields-with-wordpress-menus/
Which it does, but then I don’t have a field to select that choice and represent as a menu.
I guess I could put each of the menu choices (there are only 3 I need) in a template and then display the template using a shortcode populated with an ACF field. A bit more convoluted but should work…