I think it’s fine to specify a “category” when asking for gift ideas if you have a preference. “I’d like to buy a Suzy a toy, a book, something for her room...” If you’re just vaguely asking for “ideas,” then be prepared you may get some suggestions that seem odd or not very exciting from your point of view. As I type this, my kid is sitting next to me carrying on, once again, about the.... sigh, I’m almost embarrassed to even post this.... D.B. Cooper hoodie the actors on his favorite tv show wear. This ridiculously stupid show that my son is obsessed with has a storyline about solving the D.B. Cooper case, so now I have a 3 year old who is infatuated with all things D.B. Cooper. That hoodie is for sale online, and if you showed up with it as a gift he’d lose his mind. No toy would match the excitement he’d feel for that hoodie. But, if you asked me for gift ideas for my 3 year old and I told you a D.B. Cooper hoodie...
Archie’s too young to ask for specific gifts so, if this story is true and to be taken at face value, I imagine it went something like this:
Queen Grandma: What does Archie want for Christmas?
Meghan and Harry, looking around at the ever-growing mountain of toys their kid doesn’t play with: Oh, you know what? He goes crazy for waffles every time we go to brunch. He’d love to have waffles at home!
Queen ships them a waffle maker and now the kid wakes up every morning excited to eat waffles. Sounds like a pretty good gift to me. Harry and Meghan can certainly afford to buy a waffle maker if they just wanted one for themselves, so I can believe the idea was offered up in an honest attempt to give grandma a gift idea he would enjoy. It sounds like the problem with your sister was that she wasn’t giving suggestions of things the kids actually wanted. Unless they were young enough that she had to guess at what they might like, because that can be hit or miss. The toy I suggested to my MIL for the 3 year old was not a hit this Christmas.

But he likes those curtains!