We do use the Giftster app, which I like because people can put up their wishlists and sizes etc. And then you can mark if you are getting the “sweater” for Susie so I don’t buy one too.
I can also create my own secret lists in Giftster, which is where I jot down gift ideas but a spreadsheet sounds a little better long term to also remember what items I have already given (some people have gotten multiple car jumping cables!) and if they were a hit etc.