Second sentence mentions an API, but then, no API docs anywhere...?
https://github.com/Invisible-Computers/image-gallery/blob/ma...
I admit that this is still a bit rough around the edges...
As a simpler alternative, if you just want to build some layout for yourself and you do not need user management, you can simply render it as an image on the internet and point the device to it:
https://www.invisible-computers.com/invisible-calendar/image...
Wait? It's always proxied through your service? So there is no way to show something on the screen without you also being able to see it? That's a big nope for me.