I just noticed that the PHP version I was using (PHP 8.0.22) was compiled specifically to exclude PDO support.
According to this post, it isn’t really possible to use a custom version of PHP to run a Local instance. So if the version of PHP I want to use is compiled without PDO support, there’s nothing I can do, as a user, to fix that.
I tried the next PHP version available, and what do you know? I now have PDO support!
Is there any way we can make sure every version of PHP in Local is compiled with all of the common extensions? This is really important, in my opinion, because otherwise people who use one version over another might run into PHP errors due to an extension being missing. I would hate to find out this is a common issue with Local, as it makes it a headache to use, instead of being “[a]n effortless way to develop WordPress sites locally.”