I was able to go to the Conwy Archives and the Library today so I had a quick look at a few things but haven't found a lot. You are probably aware of all the info on the Census anyway but I'll just repeat it in case you are not.
In the 1891 Census David Roberts lived at 1 Ty'n Ffynnon in Tydweliog with his wife Ann and their children Jane H, Annie, Evan, Willie H, David and Hughie J. The Census showed that they all could only speak Welsh!
In the 1901 Census they had moved to Llandudno and lived at Ingestre Cottage, Ty Gwyn Road, Llandudno and they were all there apart from Ann who must have died in the meantime.
In the 1911 Census they were living at Ty Fry ( House aloft) in Old Road Llandudno
I took a photo of Ty Fry today and it's the yellowish property on the right in the photo
Was your Grandfather still living in Llandudno in 1922 because there was an Evan Roberts living at 5 Prospect Terrace off Ty Gwyn Road and he was a shoemaker by trade?
I couldn't find details of any burials for the family at St Tudno's or Llanrhos but there are ways of tracing those on line. Unfortunately I am pretty useless on the computer but there are others here such as Suepp and Dwsi who are experts if you need help.