Will Didnapper 2 receive future updates, and will it work on Android via Joiplay? I am interested in maybe buying the game.
We don't have any further content updates planned, as we've moved on to work on other games, and so the only updates would be bugfix patches and/or updates to fan-made mods.
As for playing the game on Android, that is not something we have official support for, but we have heard that some players have been able to run the game to some degree via the JoiPlay emulator. If you do want to test whether that works for you before buying the game, then I would recommend trying with the free demo first (the demo is the first 3 chapters of the full game).
RPG Maker MV and MZ allow Android exporting, but the developer has to support it. However, the assets are designed for computers in mind which would have to edited for the Android phones' smaller and wider screens mainly the UI and the image-based scenes (misleadingly called CGs). If played as is, the game would have bars on the side since the aspect ratio is different from the phone. You can see this on a phone by watching my Truth playthrough on YouTube as the videos are recorded in 3:2 aspect ratio. Of course, I'd imagine the lock picking would need edits for touch screens since it doesn't seem to work without a keyboard and mouse. In fact, you wouldn't be able to get past the first chapter since there's a required lock picking segment right after the first escape system.
If you have a Steam account (although you need a PC, preferably one on Ethernet as well your phone on a strong connection), you can use Remote Play to stream Didnapper 2 to your phone using Steam Link.