For Schwab:
Follow the instructions at
https://screenshot.googleplex.com/8rYj3UYcgwKnW8r
Go to
https://gsu-calculator.web.app
Click the button and upload the JSON.
It should download a XLSX. Retrieve the value under TOTAL.
Profit!
Run
cd gsu_cli
dart pub get
dart run bin/gsu_cli.dart --inputFile EquityAwardsCenter_Transactions.json --templateFile ../gsu_app/assets/gsu_template.xlsx --outputFolder .