Yup, you're right, currently function by function rules are not available.
However, you can make multiple SwiftLint yml files! Here's what the docs say:
Nested Configurations
SwiftLint supports nesting configuration files for more granular control over the linting process.
Include additional .swiftlint.yml files where necessary in your directory structure.
Each file will be linted using the configuration file that is in its directory or at the deepest level of its parent directories. Otherwise the root configuration will be used.
included is ignored for nested configurations.
So basically if you can group those functions together, they can all have their separate SwiftLint yml file. Not the best solution, but maybe the best solution for the current offering.