I’ll look back at my paperwork - both those removeable panels got damaged by the main dealer’s “Fiat trained technicians” during the warranty repair of my windscreen (admittedly now a few years back*). I had them supply replacements at their expense. They easily break if pulled away from the wrong end. It’s easy to remember which is the right end… because it’s the right end

-- and need to be removed at least annually to clear the small drain hoel behind them.
More recently the little spring clips those panels locate into (at the right end of each opening, in the main scuttle cover) have broken. Although not listed as a separate part for the Panda, they are for the 500. I’ll fish out that number too.
(*another example of why I steer clear of ‘dealer servicing’…)
EDIT: Just spotted -- you already have the part numbers - they are moulded into the panels and are (as you say) 735 490 221 and 735 490 223.. you'll also spot 'GDX" moulded in there, meaning right hand drive.
And the spring clips they locate in are here:
https://www.aecar.co.uk/products/clip-scuttle-panel-trim-dashboard-trim-abarth-500-595-60507674