I'm looking for an online survey platform which would allow participants to input information into a blank interactive online spreadsheet. The spreadsheet would be blank for each individual participant and I would then be able to export the collected data into a CSV file. Does something like this exist?
I'm not sure I understood you right. By "blank" you mean a completely empty table without table header? If not PollUnit might be something for you.
If you create a poll of type "Free Table", you can define columns. Your users fill in the rows.
CSV and excel export is only possible in the payed accounts.
At https://pollunit.com/en/table you will find some examples.