ISTR (from an abortive combinatorics course) that there's a commonly used encoding that provides 3 bits of ECC for each 8-bit byte. Could this string be 3 simple bytes with ECC?

I'm a little unclear about where exactly this works in PostgreSQL. It's true that, for stored procedures (functions), there is a plugin system for the stored procedure language. But there is only one SQL dialect that can be used outside of stored procedures. The new DO command arguably expands this, but it still looks a lot like a stored procedure body.

Tiny quibble: I don't know if you could call it the "primary language" since it's just as primary as all the others. I recall a time when I had to enable it in each DB that needed it -- perhaps if it's included by default it is now slightly more primary than some others...