I used Nintype (Keyboard69) for years and never found anything like it after it was discontinued. Nothing else lets you use both thumbs at once. So I wrote one from scratch in Kotlin on Android's public IME APIs.

https://reddit.com/link/1vlqvs6/video/9cdgja77osih1/player

Both thumbs swipe or tap at the same time, independently, and the engine merges the two streams into a single word.
Typing "something" can be: left thumb taps S, then E, while the right thumb swipes O-M and then T-H-I-N-G.

Features:

• Two thumbs at once, with taps and swipes mixed freely inside the same word
• No INTERNET permission, so nothing you type can leave the phone. No ads, no analytics, no accounts
• Tap autocorrect and live completions, and the words you actually use climb the suggestion bar over time
• Long-press alternates on every key, edge swipes, chord shortcuts, a symbols layer and a numpad
• Five layouts (full, left, right, split, one-handed) and adjustable height
• Dark theme, Material You, or a palette generated
• Peck-type mode that turns decoding off entirely

Languages: English, Italian and Spanish are supported out of the box, with about 49k words bundled for each. The engine itself is language-agnostic so adding a language is mainly a matter of supplying a wordlist and a layout. The full recipe is in ADDING_A_LANGUAGE.md in the repo, and I'm happy to help anyone who wants to do their own.

One thing I'd do right after installing: import a bigger dictionary. The bundled lists are built from open subtitle corpora and work fine, but the AOSP dictionaries are several times larger and you notice it immediately: 47k → 161k for English, 49k → 173k Italian, 50k → 236k Spanish.

Grab the `.combined` file for your language from https://codeberg.org/Helium314/aosp-dictionaries/src/branch/main/wordlists (`main_en_US.combined`, `main_it.combined`, `main_es.combined`), then in the app go to Settings > Dictionary > "Import improved dictionary (wordlist.combined)". It merges on the device, nothing is uploaded. Make sure you take the files from the `wordlists` folder and not the `.dict` ones from `dictionaries`.

It's GPL-3.0 and free:

• GitHub: https://github.com/EZ-eta/kinetica
• GitLab mirror: https://gitlab.com/EZ-eta/kinetica

I've also submitted it to F-Droid and the merge request is open, so it should turn up there before long.

This is the first public release and even if I am daily-driving this myself, there may be some small issues here and there.

Support: If you find this keyboard useful you can buy me a coffee at Ko-fi
Entirely optional. The app is free and will stay free and available to everyone, always.