I use a compact mode in AnySoftKeyboard, which might work well for tiny screens! The keyboard is only 5 keys wide, and most keys have two corresponding letters (double tapping to type those letters). It is quite nice even on normal sized phones for individuals who are prone to mis-tapping resulting in typos like myself, I recommend giving it a try.
No way, Samsung already supports it?! Do you know what version of Android or OneUI supports it?