I would kill for a built in save system. I don’t think we’ll be getting one any time soon, however. I believe some staff has expressed in the past that a save system goes against replayability and impact of choices (which I don’t agree with). @ChanceOfFire has summed it up pretty nicely, but here’s the link to an unofficial save manager that still works by the incredible @yasirkula. They’re also incredibly helpful. You can also “cheat” by looking at the game’s code if it’s published on Steam. For mobile, however, I don’t think there’s any way 
Keep making noise about it? 
Squeaky wheels get the grease and all that. I totally agree with you btw. Virtually every other VN has a working save system except CoG, which needs it most!