Wear marks on chains
It makes no real difference - the rollers in a chain turn all the way around, and the wearing surface is the internal diameter of the roller, not the external diameter of the pin.

There are some fancy chains which have a marked outside and an inside, and may state a top and bottom too, but this is more about matching the shifting lands and pins and ramps on a cassette.

Some chains are asymmetric in their outer plates, which looks "wrong" if installed upside down.

Other chains, noticeably half-link or BMX chains can have plates over the top, so the two outer plates are one piece folded over.  This is done for strength, and cannot be flipped either.   These chains don't work with derailleurs so you're unlikely to have one.

 A chain that can be reversed but not flipped.