Ability to play smaller discs was normal in most CD-ROM and DVD players for many years before the Wii. A few people (probably half of whom have HN accounts) used to give out mini-CD business cards...sometimes even with truncated edges so the disc was not entirely round: https://www.duplication.com/cd-business-card-duplication.htm

Yeah but most of the optical drives that support this have trays or are top loading. It’s a little more counterintuitive to have a postbox-style drive (I don’t know what they’re actually called) that supports different sized discs.

> postbox-style drive (I don’t know what they’re actually called)

Slot-loading.