[r1b]

It’s strange to me that the interop story here only considers compatibility with GoogleSQL.

These days, we have tooling that can generate an IR for SQL and transpile it to any dialect (see: sqlglot).

Doesn’t coupling SQL syntax to dialect-specific SQL semantics throw a wrench in this?

[sagarm]

You could implement a family of poorly defined dialects using SQLGlot, sure, in the same way you could define a meta-language targeted at Algol-family languages. That's not a substitute for adding language features.