I have been looking all day for a FOSS keyboard that’s under active development. It seems like more of not all of the ones I’ve seen recommended haven’t been updated in over a year some three years. I don’t mind if it’s a long time between updates but I want to know bugs will be fixed eventually.
Open board has an active fork here: https://github.com/Helium314/openboard
It has typing suggestions, backspace and space bar gestures, and now some custom theming. Though it does have a weird bug with backspace behavior in the jerboa app- so does the original openboard and aosp keyboard that openboard is based on.
Its not available on f-droid, though hopefully that’ll change in the future, but you can install the apk from the releases tab on github, or you can use obtainium to do that for you and it’ll let you know when there’s a new release