Having just returned from PMI with Ryanair, there were posters all over the airport stating that you could take a duty free bag on board as extra to your normal hand luggage. However on closer inspection there was a star at the end of it and at the bottom of the poster it stated that this was subject to the airline and to check with them first.
Iirc at LPL the duty free shops signs say Ryanair will allow a bag of shopping bought in the shop. I'm paraphrasing, but Ryanais is mentioned by name.