So, a long story made short:
I had a wiki, I have the SQL. I tried to set it up on localhost using MAMP. Finally got rebuildall to do something, after I was able to get update.php to work.
I got the following:
[a5cbdb0fd715fc3ef188c065] [no req] Wikimedia\Rdbms\DBConnectionError from line 800 of /Users/carter/Sites/id8tionist/mediawiki/includes/libs/rdbms/database/Database.php: Cannot access the database: No such file or directory (localhost)
Backtrace:
#0 /Users/carter/Sites/id8tionist/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(1028): Wikimedia\Rdbms\Database->reportConnectionError(string)
#1 /Users/carter/Sites/id8tionist/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php(670): Wikimedia\Rdbms\LoadBalancer->reportConnectionError()
#2 /Users/carter/Sites/id8tionist/mediawiki/includes/GlobalFunctions.php(2858): Wikimedia\Rdbms\LoadBalancer->getConnection(integer, array, boolean)
#3 /Users/carter/Sites/id8tionist/mediawiki/maintenance/Maintenance.php(1253): wfGetDB(integer, array, boolean)
#4 /Users/carter/Sites/id8tionist/mediawiki/maintenance/rebuildall.php(44): Maintenance->getDB(integer)
#5 /Users/carter/Sites/id8tionist/mediawiki/maintenance/doMaintenance.php(92): RebuildAll->execute()
#6 /Users/carter/Sites/id8tionist/mediawiki/maintenance/rebuildall.php(67): require_once(string)
#7 {main}