The ANLTR organisation on GitHub manages a repository with example grammars. You find the ones for SQL here.

Most of the 3rd party grammars cover a large subset of the underlying languages. They define what they cover in ANTLR or by EBNF. However, they often do not define which versions they cover and they do not define what they don’t cover. As a result, you have to try if the grammar is sufficient for your use case. Furthermore, you have to assess if it is sufficient for future use cases and if the grammar will cover the changes in newer versions. This is very difficult without a clear scope.

IslandSQL is different. It defines the scope. The Database Management Systems including the grammar versions and the statements. The statements that are not in scope are kept as hidden tokens. They do not lead to parser errors. And the known limitations are documented.

See Database Management Systems and statements.

See limitations

See SQL:2023.

Yes, but they are part of a private repository.