can you show pictures?

I'm not sure how to upload a photo, but I'll try. What is the general rule regarding the sink and the faucet being the same material?

You have options!

You can go with either of the options, both would look nice with your described finish palette. Sometimes two of the same finishes have some slight tone or metallic differences which make the match of finishes a mismatch. Unless you can compare the sink and faucet together before purchasing, a chrome faucet might be safer. Perhaps go with chrome hardware to tie that same level of reflectance into your space. Another option would be to consider a faucet in a finish which provides a high contrast to make all of your finishes pop like a matte black.

Best of luck with your project!

Following.