If I can name these files whatever I'd like, what should I name them?

It's up to you! Here's a few options:

• Default to the existing terminology: schema.yml (though this does make it hard to find the right file over time)
• Use the same name as your directory (assuming you're using sensible names for your directories)
• If you test and document one model (or seed, snapshot, macro etc.) per file, you can give it the same name as the model (or seed, snapshot, macro etc.)

Choose what works for your team. We have more recommendations in our guide on structuring dbt projects.