Has anyone managed to implement IndexNow on Shopify without root access for the key?

[OliviaMichaelCo]

As per the title really, the Bing side points to a Shopify post for the solution, but it doesn't mention how to get around the need for a key to verify the request.

I'd like to implement IndexNow and can get everything working except for authenticating, because I cannot get root access to save the key that is required.

Without paying for an app, has anyone figured this out?

Thanks.