How to specify a different tmp directory via GF_ variable

I don’t see in the docs how to specify a different tmp dir via GF_ environment variable.

Is there a way to do this, if so how?

We can only run our containers with readOnlyRootFilesystem and switching the tmp dir will help by mounting emptyDir for /othertempdir` or using a PV (kubernetes)

If all your containers have a read-only root FS, how does any app, which is
expecting to use /tmp, manage to work?

I would have thought that making /tmp at minimum a RAMFS, if not externally-
or bind-mounted, would be a necessity for containerisation.