Formula for "Select Items Initially" in List with Selection

I am using a Checkbox with a List Resource bound to the component. There are 10 available selections. An app user will have selected some number of these during signup and they are stored in an object with objects value (id is the key) matching the id in the list resource. What I am trying to figure out is how to populate the checkboxes when a user arrives with what they already selected. It seems like I can use the “Select Items Initially” with a formula but am struggling to return an array of true/false values to populate the checkboxes. Does anyone have any suggestions?