Q:

Should the Sage Advice Compendium be considered a 1st party resource?

Should Jeremy Crawford's Sage Advice Compendium found here be used as official Wizards of the Coast content or rather as his own home-rules?

A:

Per the description at the top of the Sage Advice Compendium:

These are the official rulings of Jeremy Crawford, the game’s lead rules developer.

Other pages on the Wizards of the Coast website also refer to Sage Advice as "official rules answers" or "official clarifications of D&D rules". It's definitely an official, first-party source.
(D&D designers' individual tweets may not always be official rulings of the rules as written, but those that are in the Sage Advice Compendium are indeed official.)

