These neoprene gloves are a good choice for biking in heavy rain. They won’t stay dry but neither will they get cold. They aren’t made from too thick neoprene, so they offer only medium padding, but I expect that this will be enough for most. At around 50€ they are somewhat expensive for what they are. You could just buy some non biking specific neoprene gloves and not be much worse. Yet these are good for sure.
The gloves have touchscreen pads on thumbs. (Credit: GripGrab. Fair use.)