Appium Server 2 beta - NODECONFIG format

For Appium 1.2x I use a nodeconfig file - I’ve been using this approach for years. However, it isn’t recognized by Appium 2 - I get this error:
appium server: error: argument --nodeconfig: invalid json value: '/Users/automation/config/nodeconfig-ios-lgc.json'

I tried putting individual values in the command line directly, but everything gets rejected - e.g.:
appium server: error: argument --nodeconfig: invalid json value: '"browserName":"iPhone_8"'

Can anyone supply a working example of what Appium 2 expects for NODECONFIG?

So I think that Appium 2 uses Selenium Grid 4, which apparently no longer uses --nodeconfig. Apparently it now uses TOML file. Please see here:

https://appium.io/docs/en/advanced-concepts/grid/
https://www.selenium.dev/documentation/grid/configuration/toml_options/

NOTE: I have not done this, just trying to help.