Click the thing on the taskbar that looks like a plug. You may need to configure the parameters first in your platformio.ini file if the defaults don’t work for you:
monitor_speed = 115200
That still doesnt make an input box like in the arduino ide.
You might not be able to do it the same way as IDE that has input box, but you can click the mouse at end of monitor window and type. Note it will probably send each character as you type it in, instead of only when you hit send or enter key
yup, had to change some parameters to send using enter.
Found an alternative Serial Monitor Extension that fit my needs.