The biggest thing keeping me from switching away from Gboard are things like the Japanese and Chinese IMEs. I have yet to find an open source keyboard with both of those, while also allowing me to switch to English.

Edit:

Clicked on the article. Clicked on the Trime and Fcxit5 and plugins links. It might be suitable in the future. Hoping this isn't a situation where I finally find a solution and then the devs suddenly disappear without a trace.