AFAIK FlorisBoard will support gesture typing with it soon (they already support normal typing with it) and it’s FOSS!

Sangaline/DGHP and NALMY come to mind. The first tries to optimise for uniqueness of gestures and the second for distance travelled, both meant for hand gliding typing

I like SimplyTranslate from F-Droid and RTranslate from GitHub. The second one also has a really cool live conversation mode where it can, through voice detection and TTS, interpret back and forth between two people.