I can’t give you exact specifics of how to do this, but it should be possible. I have several examples of dynamically populating acf fields based on other acf fields here: https://github.com/Hube2/acf-dynamic-ajax-select-example
This one has an example of dynamically populating a repeater, including making sure there are the correct number of rows: https://github.com/Hube2/acf-dynamic-ajax-select-example/tree/master/dynamic-repeater-on-category
This one has an example of dynamically populating an image field: https://github.com/Hube2/acf-dynamic-ajax-select-example/tree/master/dynamic-fields-on-relationship
The only thing I don’t have a specific example of is getting the currently selected values from a gallery field. There are also a couple of examples of making ajax requests to get values for fields.
