Hi @vikna ,
Since all data is in the Gallery. Whatever be the DataSource, make sure it has a Unique Identifier for those records.
Now you can create collection of records where those IDs will be stored for toggle 'ON'.
I've made a similar scenario,

If you see that I've shown label that is Visible based on those records where toggle is selected.
Toggle Properties,
OnCheck:
Collect(colShowPopUp,
{
ID: ThisItem.PrimaryKey
}
)
OnUncheck:
RemoveIf(colShowPopUp,
ThisItem.PrimaryKey in ID
)
For Visible property on your Pop-Up Control (In my example, I've used label contol)
Visible:
If(ThisItem.PrimaryKey in colShowPopUp.ID, true, false)
Hope this helps.