Unless there is an open source app, the next stop will be the piracy sub. It may be able to work if you obtain an apk and patch it to think it's paid. While there, it would also be worth defusing data mining components.
And it's a offline version so It will not connect to android.
Not sure I follow, but are you sure about that? However, some things to check for:
does it have the network permission?
AndroidManifest.xml inside it contains if it does, but also app manager or plenty other apps can tell if so because it's relatively straightforward to tell
does it to interprocess communication with other apps? through Intents or some more convoluted way, there's plenty. That's hard to tell.
Most modder nowdays not just provide paid version of app but also cut down most of telementry and tracking stuff. Also I check AndroidManifest it doesn't have any unnecessary permission but still I am not gonna use a close sourced keyboard.
I'm trying it out and it feels oddly comfortable. Obviously muscle memory from the regular layout is getting in the way but I can feel that the devs are onto something.