Where Can I Locate Debt Metrics for Any Stock?

This can be found in the Balance Sheet card of every stock's symbol page or in the Debt tab in your portfolio.

Visit https://seekingalpha.com/symbol/AAPL and scroll all the way down to find the Balance Sheet card

Debt tab in portfolio - https://seekingalpha.com/account/portfolio/debt

If the Debt tab is missing under portfolio, then you can add it by clicking on Add View