Gateway Metrics without a module

I know that within a module you can add custom metrics, that can be shown on the gateway webpages dashboard.

However I have a project that is using a singleton to manage a bunch of variant threads performing specific tasks. This is all in python, and not done through a module, so I was curious if I am able to add my own metrics directly through project based scripting?

My guess is something in com.inductiveautomation.ignition.gateway.metrics however an example of where to even start would be fantastic.

I know that I could create my metrics as tags, and then create a dashboard that looks at those tag values, but being able to use the gateway webpages dashboard is ideal in this scenario.