It is “possible” to publish your project to multiple devices. You can publish a single project to any amount of players you have purchased/control.
Pixel sizing is a big issue however, and I agree it can get a bit complicated. Don’t quote me on this, but I believe tablets will try to scale the presentation as best they can. But it’s always best to deploy to devices capable of the same size, in my opinion. So do some research up front beforehand.
Alternatively…if you’re willing to put in the time for this. In theory, you could create a semi-responsive presentation. Since every asset has a size and position, you can use bindings to set relative sizing by binding to the System Info Interface Asset…I think there is a screen resolution property in there. I think this would be a lot of work, and I’ve never done it before…but if you go that route, I’d love to see how it turns out.
Lastly, I don’t believe PowerPoint imports any interactive elements. I think it only converts slides to PNG images. But maybe one of the IF staff can respond to this and back me up. Good luck!