Here’s the thread about PicoMite versions:
If your PicoCalc shows version 6.00.xx then it’s running the latest. But I’m not sure that’s even been made available yet. The thread also includes a build for the Pico2 (a bit further down the thread), since it requires different firmware than the Pico.
There’s also some relevant information at the end regarding which USB connector to use when programming, powering, and potential issues using the keyboard when one of the USB cables is still plugged in. Probably worth reading the entire thread. 