But I with my full 10kg carry on luggage, won't be buying anything in the shops, because Ryanair say I have to stuff whatever I buy in the shops into my carry on luggage.
You of course miss the business opportunity here.
Agree with airline for a very small fee that passenger purchases made up to 30 minutes before departure are loaded onto plane as check in baggage / carry on handed to passenger at landing.
or
Purchases Air Freighted and delivered to customers door within 24 - 48 hours.