It's absolutely disgusting to me just how many people fail to properly and consistently clean their earbuds. To me, wearing dirty earbuds is equivalent to rewearing dirty socks.
I clean my earbuds everytime I finish wearing them and it's honestly become such a chore. Having hardware designs that are easily cleanable are so important. I really wish earbud manufacturers would stop putting hard right angles and recessed charging contacts into the body of earbuds because they just attract hard to clean gunk. Also, eartips should be round bulbs instead of a mushroom shape, that way it doesn't accumulate gunk on the underside of the eartips, requiring you to tediously invert the mushroom just to get all the earwax out.
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.