When people want privacy they will inevitably have to give up usability. I ditched Swiftkey for an open source Android keyboard that doesn't connect online or asks for any permissions. Its CRAP but it doesn't leak.
I can't speak for GP, but I switched to Hacker's Keyboard[1] which doesn't support gesture typing. I'm pretty happy with it, though it's pretty barebones (it doesn't even turn on the phone's radio). Took a bit getting used to -- the recommendations are different and it felt like the key hitboxes weren't the same as gboard, but it felt pretty familiar after a couple of weeks.
You should check out MessagEase keyboard. It is so accurate for me that I don't even need corrections. It takes a little bit of time to get used to, but once you get the hang of it, it's super fast.
When people want privacy they will inevitably have to give up usability. I ditched Swiftkey for an open source Android keyboard that doesn't connect online or asks for any permissions. Its CRAP but it doesn't leak.