The problem with ‘canon’ can usually be summarized with the saying, “too many cooks in the kitchen spoil the broth”. You’ve got your Don Rosa, Carl Barks, Elisa Penna, Vic Lockman, Marco Rota and many, many others, all of whom have had a chance to write Duck family comics and input their own take on canon. Was Donald canonically raised by Grandma Duck? Yes, in a few cases we can trace back to instances that show little baby Donald Duck with Grandma Duck. This Is Your Life, Donald Duck, a book from 1960, shows Grandma Duck raising him.
I believe we also get from this book the reasoning behind why Donald wears a sailor hat; apparently he bonks his head on the ground like that because he hates the silly bonnet Grandma put on him. She takes him to see a naval ship one day, he keeps bonking his head on the deck but in doing so he alerts the sailors that the bulkhead is full of water through the unusual sound his head was making against the deck. As thanks, one sailor gives Donald his cap and poor Donald never has to wear that silly bonnet again.
Now both This Is Your Life, Donald Duck and another comic called Happy Birthday, Donald or From Egg to Duck were both written by Marco Rota, who was stuck on the concept of Donald being ‘found’ by Grandma Duck and raised from an egg. Rota didn’t care for the concept of Della and never acknowledged her existence so to him Donald doesn’t have a twin sister. Of course that also means he didn’t believe there was a Hortense or Quackmore to conceive baby Donald.
Unfortunately at this point in time there aren’t any comics that go into any sort of explanation behind the current location or circumstance Hortense and Quackmore are in. From The Life and Times of Scrooge McDuck we know they were a real couple and they’re the parents of Donald and Della Duck but no one’s given us anything to go on where they are now or what happened to them.
Right now the Netherlands is releasing one page comics going over a lot of baby Donald’s first experiences (Donald’s Eerste …), a lot of which include little Della, Gladstone and Fethry. They’re cute, so far there’s been one on finding his first Easter Egg, his first dance lesson, competing with Della is prominent in a few of them. Those are definitely worth finding if you can, though you might need to have them translated from their original Dutch. yourstrulychitchat here on tumblr has a few uploaded.