Adding HMAC Firewall Validation for SHA256

Hi!

I was wondering if there was a supported function provided by Cloudflare that can be utilized in an expression to conduct HMAC SHA256 validation, with a signature digest being a hex encoded string, without the usage of a worker?

Looking at
https://developers.cloudflare.com/ruleset-engine/rules-language/functions#hmac-validation
it seems the only supported form is base64-encoded MAC natively.

Thanks!