Again, what you are seeing for a relation in the data tab is not an actual list that’s contained within a cell. It’s just a visual representation of the records it is linked to in a different sheet and only displays the values from the first column of the linked sheet.
If you wanted an actual list of linked records inside of your spreadsheet for visual reference, I would create a column and use a query or filter function combined with a join function. Something like this:
I think I understand what you are asking for, but that is not the function of a Relation. A relation is to create a link (like a URL)…not to pull in the contents of that link. If you had a Relation that linked to a million rows in a different sheet, would you want one cell to contain the entire row contents of all one million records?
I understand what you are saying with the functionality of an airtable database, but airtable is a bit more complicated that google sheets and essentially it’s a hybrid between a database and an app. It’s doing the same type of linking that glide does. A quick search of exporting airtable data to CSV led me to this post, https://community.airtable.com/t/exporting-data-out-of-airtable/14847/3 which just creates a column of comma delimited data from the related records in airtable. It doesn’t give you a functional link to another table, just a list for visual reference.
If you really needed that list, I would just create a column and populate it yourself using formulas.