I made a program to help with using desktop applications on #LinuxMobile called Touchpad Emulator, it lets you use the entire screen surface as a laptop-style touchpad and uses either the volume buttons or alert slider (OnePlus 6/6T) to switch from touchscreen to mouse mode. Also with the next Phosh there will be a screen scaling quick setting to quickly scale down for desktop apps!
https://gitlab.com/CalcProgrammer1/TouchpadEmulator
I used to have KiCAD on my PinePhone Pro!