Last June, Gboard started rolling out a split keyboard for foldables, and it’s now appearing on Android tablets.
Gboard’s split keyboard places an equal number of keys on the left and right when the “Split layout to include duplicated keys” option in Settings > Preferences > Layout is enabled, which it is by default: “When the keyboard is set to split layout, some keys will be duplicated on both sides.”
Play Store: Gboard - the Google Keyboard - Apps on Google Play
APKMirror: https://www.apkmirror.com/apk/google-inc/gboard/