i use Thumb-key,
its very strict about privacy,
and all about swiping inputs.
but its a rather radical concept.
i used hacker's keyboard a lot,
but i never used swiping before Thumb-key,
so i dont know how well it supports swiping.
I also used Gboard a lot, because i really like the clipboard functionality,
but thats obviously what you are trying to get away from.