Phones make great Christmas gifts... when they're not expensive
There's a reason we really love Samsung phones. Not only are they much cheaper than iPhones on the used & refurbished market, but they also come with modern designs that make them feel new, even a few years after their release. Take the Samsung Galaxy S8, for example; this phone was released in 2017, and it's still receiving security patches. It isn't getting the latest and greatest Android versions anymore, so it won't feel quite as modern as a Note 10, for example, but if you want a great Android deal for Christmas, you can't go wrong with an S8.
The S9 is another great Samsung Christmas deal. Although it is very similar to the S8, you can expect longer security patch support since this phone is a year newer. In addition, you're also getting an upgraded camera, a better-placed fingerprint scanner, and a slightly more ergonomic/slimmed-down chassis.