I don’t know much about programming, don’t stress, it’s all just too much discussion of possibilities. I wonder if the Glyphs mini can turn the iPad into a Wacom and use it as a hand-drawn input tool for Glyphs. This eliminates the need to port the entire Glyphs to the iPad. Non-professional advice.
You can use the iPad as an external monitor. The functionality is called Sidecar. But there are some apps that enabled the functionality before Apple implement it.