When filing you just need to remember what you paid, roughly, and subtract it, and make a little spreadsheet for the IRS.
You need the receipts or documentation once you get audited. Can be purchase receipts, or value and purchase year, at which point you could use ebay to determine the value, for instance.
Note that any of this is only relevant for your 2024 tax filing (for the 2023 tax year); if I understand right, the IRS is ignoring paypal in 2023.
In theory, even if you sold using F&F, you'd still have to do the same thing.