Cheer GIFs are both iMessage Stickers AND an iOS keyboard for pasting into any messaging app that accepts image pasting. It includes 61 cheer-themed stickers (40 animated + 21 static), all in 3 hair/skin tones. Cheer GIFs works on iPhones® and iPads® with iOS 10 or higher (sorry, no Android).
The Cheer GIFs keyboard (but not iMessage stickers) requires "Full Access" so it can access the clipboard for pasting images into your apps. Apple gives a scary warning when you enable Full Access, but rest assured — Cheer GIFs does not collect, record, monitor, or transmit your keystrokes, images, or personal information. I promise!