It depends on whether the knowledge is about the employer or about the field. Knowledge of a system the company built, and of how it is applied in its markets, is what the classification reaches. Being unusually skilled at a technique used throughout the sector is not, however rare that skill happens to be.
The petition has to describe an asset the employer owns
Reviewers approach this classification expecting to be told that an ordinary specialist has been dressed up, so the drafting has to defeat that expectation with specifics. For Oceane the useful material is documentary: the design notes for the traceability schema, the validation protocols written for the company's own purge cycles, the internal standard operating procedures she authored, the release history of the software, and the record of who else can maintain it. Each of those points at the organization rather than at the industry.
Two further elements help. Show how the system is applied in the company's international sales, since application in international markets is part of the definition. And show what would happen without her, not as a compliment but as a description of the implementation timetable.
What does not help is a letter listing her certifications, or a claim that few people anywhere understand shellfish depuration, both of which describe a person the field could supply.