There is an add on that I use for ACF https://wordpress.org/plugins/acf-enhanced-message-field/
It lets you add PHP directly to a message field. With it you can show images the way you want to do.
When it comes to the acf/load_field hook, while the documentation here is pretty simple and only covers dynamically generating choices, you can in fact change almost anything about a field settings with the exception of the field name, field key and field type.
You could theoretically change the “append” value of the field to dynamically display the image, but I’ve never tried this.
