i dont like "Simple" apps. the most of them i tried offer also a paid version. the only one i use is "Simple Gallery Pro" from f-Droid. "Pro" means "paid", but from f-droid its free. i tried also another keyboards and got stuck on the google keyboard, KeepassXC for the security keyboard. "simple" does not mean "small".
they are two different apps by two different authors. it is the smallest, simplest, no-frills keyboard app there is.
^ Google in their infinite wisdom recently removed it from Playstore but it remains on F-Droid. That`s the one I`m using, light and fluff-free, tested the Simple Mobile Tools version but found the 'original' better.