@BOOKHOUSE We've called _some_ of them "solo gamebooks" for many decades, but that term used to be limited to those with self-contained game mechanics. Those with decisions only were CYOA, and the cousin of gamebooks attached to non-self-contained mechanics were RPG solos/RPG solitaires.
But over the last few years all of those terms have been shredded into a confused muddle by the rise of #SoloRPG journaling and related games that introduced new forms to gamers who never played the older ones.