tl;dr: Remove eartips, wipe gently with a lint-free cloth, add a small amount of water if you’re having trouble scrubbing anything (without getting water inside). If you have Pixel Buds Pro, they also recommend using an adhesive putty if you’re still having trouble removing any debris with the cloth.
Google’s instructions, linked from the article:
https://support.google.com/googlepixelbuds/answer/9112670?hl=en&ref_topic_7544331
tl;dr: Remove eartips, wipe gently with a lint-free cloth, add a small amount of water if you’re having trouble scrubbing anything (without getting water inside). If you have Pixel Buds Pro, they also recommend using an adhesive putty if you’re still having trouble removing any debris with the cloth.