I'm aware that restic offers a large number of tunables, such as RESTIC_COMPRESSION and RESTIC_READ_CONCURRENCY

The documentation is currently unclear about where these should be placed in the config.
E.g., does the backend env: block get sourced verbatim before autorestic runs commands, or do we need to add it to the location?

What's the currently accepted method for setting various RESTIC_ environment variables?