GiME

You can input Japanese, English, Korean, Chinese (simplified and traditional), and experimentally, Devanagari (Hindi, etc.) using a standard game controller (Xbox controller, PS DualSense, Switch Pro controller, etc.).

Japanese uses flick input, English uses T9 (tap input), Korean uses the 2-bol system, and Chinese is based on Pinyin and Zhuyin, so your fingers will quickly learn with a little practice, probably. Devanagari consonants are arranged clockwise from the top of the directional pad in reading order (textbook order).

You can also send text to VRChat via OSC. Since you no longer need to fumble around on the keyboard trying to touch-type or look out of the headset every time you type, the sense of immersion shouldn't be lost. I'm trying it myself, so someone else should try it too!

The IME can be minimized, so once you get used to it, you can significantly reduce the screen space it occupies.

Since it only requires slight finger movements, it might also be useful for accessibility purposes. The possibilities for its use are limitless, as far as your imagination can take you! (I mean, I can't even begin to gauge its potential.)