As per Python 3.9 is not supported 路 Issue #3700 路 platformio/platformio-core 路 GitHub, that error relates to you using Python 3.9, which is not yet compatible.
For the other library update error, see the other thread: Library update issue still unanswered - #4 by maxgerhardt. You need a more recent version of the PlatformIO core.
Greyed out update buttons after that are still subject to being fixed by @ivankravets (per PlatformIO IDE 2.0 for VSCode 馃殌 - #20 by ivankravets). According to this report it鈥檚 still happening.