My Mum was on a puree diet too, but there are some foods that are melt in the mouth...like Quavers, some little chocolate biscuits designed for 6 month old babes - (take them out of the packet and put in a biscuit box and they look like any other mini biscuit!) chocolate buttons and a few other items that I can't recall now!
I work with Speech and Language therapists and they suggested these foods, they are often used for people who have swallowing issues.
Mum really enjoyed having something to bite on, back in her diet! and would have her 'crunch - then melt in the mouth foods' as a 'side ' on her plate of soft food. She enjoyed the biscuits along with a drink too.
I will see if I can find the list I made of the melt in the mouth foods of what I could get her - or told other people to buy her as a treat.
If he smiles when he gets the flowers, how about a DVD of a gardening programme- or if there is such a thing a DVD of a walk round a garden with close ups of flowers....(a bit like those films of fishtanks!!)
Or how about an invitation for him to go with you to a Garden Centre/ RHS place/stately Home Garden/National Trust Property? to see/touch/smell the flowers - or a sensory garden somewhere?
Good luck with your Christmas thinking!