Good to meet you too @Keith ! I’d be interested in knowing more about this too.
From that SO link, it seems like you need to compile PHP with the --with-sodium flag. Here are a few things I found while searching around:
A community forum post on compiling extra extensions within Local sites: How do I compile additional PHP extensions?
And here is the libsodium link on PECL: https://pecl.php.net/package/libsodium
I’ll see what else I can find out, but let me know what you come up with!
– Ben