Ubuntu's DING extension adds new keyboard shortcuts for desktop icon selection, including multi-select, Ctrl+Space toggle, ...

If you install iPadOS 26, the reed pen is added automatically, but you might not immediately see it if you open the drawing ...

Toggle on Virtual Trackpad. Once you do that, the Virtual Trackpad will appear on your screen. You can move it around or expand it as you see fit by enhancing the size with two fingers spreading apart ...