Hi,
Welcome to community.
For the first question:
It seems like you refer to the Chart Filters button as below. If I misunderstand, feel free to correct me.
I get the screenshot when I test in PowerPoint on Windows.
However, I'm afraid this button is not available in PowerPoint on Mac. Some community members also noticed this limitation in PowerPoint for Mac.
I sincerely recommend sharing your valuable feedback via Help menu>Feedback, feedback submit by this way directly goes to the related team, this is the best way to let PowerPoint developers know your requirements and help to improve the product. Thanks for your understanding.
For the second question:
It’s not available to insert chart in PowerPoint for the web. Thanks for your understanding. I recommend you use PowerPoint desktop app to insert chart. I also recommend you share feedback via Help>Feedback in PowerPoint for the web to let the developers know your requirements.
Hope you have a nice day and stay safe.
Best Regards,
Tina