Square Enix will be releasing Final Fantasy XV: Pocket Edition on February 9, according to its website. The mobile game will be released in episodic format, but Square Enix's website seems to imply that all of the episodes will be available immediately upon the game's release; there are no dates listed for any other chapters. Chapters 2 and 3 will cost 120 yen each, or about $1.10 USD. Chapters 4 through 10 will each be 480 yen, or about $4.40. Purchasing all of the chapters individually will end up costing you 3,600 yen, but there is an option to get the entire game for 2,400 yen, roughly $22.00, or about the street cost of the console game used. This is also close to the amount you could expect from most of the other Final Fantasy ports that have come to Android to date when they first launched. Square Enix's website does not seem to specify whether the console DLCs, such as Episode Gladio and Monsters of the Deep, are included in the base game, and if they are coming later, it's a mystery as to whether users who buy the full game pass will get them when they come out.
Final Fantasy XV: Pocket Edition seeks to bring the full Final Fantasy XV experience to mobile platforms and weaker Windows PCs. The frenzied combat, sprawling environments, and long open road are all on board, but the graphics have been overhauled to minimize resource usage while still looking good. This has been accomplished by simplifying environments and their textures, and putting characters in "chibi" style, with less character and outfit detail. Aside from the question of whether the available DLC for consoles is available in this version, the graphical hit and gameplay changes to accommodate touch screens seem to be the only real difference.
The game became available for pre-registration on Google Play recently, and if you're interested, you can sign up via the button below. You'll get a notification when the game is released, and will be able to download it from Google Play immediately. Square Enix's website only lists a single release date, so it's quite likely that it applies to all chapters, and the game will be released simultaneously in all countries where the company plans to sell it. It's worth noting that there is no option to buy the entire game through Google Play; you can get the first chapter up front for free, and then purchase the rest in-app.