You need to tell us more about your set up / structure so we could tailor fit a solution for you.
But for starters, you can just reference to the thing in the RG when you click an element within a cell. It show show up as current cell’s thing / parent group’s thing (if you’re using a container within a cell)
To give them access to this thing, you would then either create a new DT linking the current user and the object in the cell or link the user directly to the object.
Again, there are tons of ways to go about this depending on your use case
Put a button in the repeating group row. Give that button a workflow. The workflow is to save that thing to a field you specify. You can then search or get that field on the dashboard.
Without more context, I don’t know what other information you may need. You have to provide it.
-Is it a Like button? Use Icons and add conditionals
-Is it just a button? Just use a button
-You only want logged in users to save it? Only show the button to users who are logged in. Or, prompt them to log in when the button is clicked.
-If you suspect that more than 20 ish items are going to be saved at a time per user, don’t use a list, just create a new datatype “saved”, that will give you information about what you saved and who saved it.
-Don’t forget your privacy rules. Only the person who saved it can access their “saved” datatype.