Parsing query in blueprint for field plugin

I have a small field plugin, for which i’d like to store some options in an .env file (rather than keep directly in a git-commited blueprint.)

        label: This gets parsed: {{ kirby.option('api_key') }}
        type: myCustomField
        help: "This also gets parsed: {{ kirby.option('api_key') }}"
        anyCustomProperty: {{ kirby.option('api_key') }} - doesn't get parsed :(

Using the query language to access site data seems to only work in the standard/default fields. Is there a way to persuade the plugin to parse extra properties for queries?

(Or alternatively, is there a ‘better’ way to achieve this? Use plugin options rather than add in blueprint?)

If you want to use query language in your custom props, the custom props need to support this, see Dynamic default number field - #2 by texnixe