What can we do to remedy the unrecoverable error we encounter for any Drush command?
Make sure your Drush commands are issued from the appropriate subdirectory of your website (change to the directory where your Drupal site is installed and try again).

Since your question did not specify that, it "might" be the reason why ALL your DRUSH commands are failing ...

Refer to this issue for other possible causes (things you may want to check).

If you recently enabled contributed and/or custom modules, try to temporary disable them to check if the Drush issue gets resolved by doing so.