Precise pointing / fat fingering is solvable for text editing and in general by using the touchscreen for relative input - like a touchpad. That's possible on the pinephone with a userland program that directly interfaces with evdev and uinput in a really simple way[1], taking the ability to run desktop software well beyond being a party trick. All it's missing is a scheme where single, double, or two-finger taps and drags are either relative or absolute to avoid having to switch modes. Or, because the touchscreen, like most, reports touch area, one might have a go at cloning force touch.
[1] https://gitlab.com/CalcProgrammer1/TouchpadEmulator
For swipe input, wvkbd[2] has experimental support that works amusingly well for how sucklessly it's implemented (see the readme), albeit only for long words or reduced dictionaries - so many possibilities, like having zsh write completions to a file. It does need a patch to not interfere with normal typing. Spacebar swiping would also be straightforward to patch (or on sxmo into lisgd instead*). Alternatively, a small key could receive a 4-way swipe gesture like the trackpoint that Windows 10 Mobile had. (btw, hey, the MessageEase patent expired...)
[2] https://git.sr.ht/~proycon/wvkbd
* <rant>I don't know how the devs tolerate the latency that sxmo_inputhandler.sh brings - handling basic OS shell gestures in a long shell script on a platform where every expansion piped to grep causes a noticeable increase in latency is very unsuckless!