Rolling Date Values in Chart Config Editor

Is there a way to reference dynamic rolling time periods for things like plotLines and plotBands in the highchart Chart Config editor within Looker?

For example - I am attempting to use the (PII Removed by Staff) attribute to shade in the previous three days. I can get it to work fine with static Unix timestamps as described here, but have not been able to figure out a way to dynamically position the start/end based on the current time.

Similarly, I have a chart that extends into the future and want to use the (PII Removed by Staff) attribute to indicate the current date for reference. Again I can get it to work fine with a static Unix timestamp value, but am unsure if it’s possible to reference the current date. I have also tried using the (PII Removed by Staff) attribute but have been unable to get it to work at all.

Basically I’m trying to figure out if there’s something similar to getTime() or now() that can be referenced within the editor but haven’t been able to find one. Thanks in advance!

I’m not sure why some of my links got removed - they were links to the official Highcharts API documentation that’s linked to from the Looker documentation here. But I guess for context without links, the attributes I was attempting to use were plotBands, plotLines, and currentDateIndicator respectively.