Are there any plans to create a Lark grammar for Lark? The only file currently in lark/grammars is common.lark, which defines a few terminals.

The authoritative definition of Lark would logically be expressed as a grammar (as opposed to "what the grammar reference says" or "what the latest version of the code parses"). Note that RFC 5234 defines the ABNF grammar that authoritatively validates ABNF specifications.