Once you've completed your GUI and Title/Logo, create a mockup of what they would look like on a tablet (iPad) or phone (iPhone).
Both the GUI and Title/Logo projects should be presented using the mockup images.
For your GUI, use your environment painting as a background and place your GUI on top of that showing on the screen mockup image.
For your Title/Logo you may use that with your environment as a background or you may use just your Title/Logo as a title screen on the screen mockup image.
This mockup image should be added to your final Google Slide Presentation.
Below is a downloadable zip file containing layered Photoshop files for either an iPhone X mockup image or an iPad mockup image.
https://drive.google.com/drive/folders/1qbUZDwsEoCKc0RqDQfNw2Uu8GwmmZrO5?usp=sharing
To edit the mockup files,
Right-click on the layer marked in Violet and choose "Edit Contents"
This will open a .psb file with a visible grid pattern.
Paste your artwork on top of the layer with the grid pattern, making sure to cover the grid pattern completely. If needed, add a layer of white or turn the grid pattern layer off.
Save the .psb file and close it.
Go back to the mockup layered file and it should update with the edits you made to the .psb file.