I have been using my iPhone like a computer for some time now. The primary thing I do with my computer is programming. I dislike laptops and more dislike carrying around one. Over about 2 months ago - I experimented using the iPad as my primary go to computer. With the multitasking enhancements introduced in iOS 11, I could pretty much use it as a primary computer with a number work apps installed: Terminus (for ssh to development Linux server), Pythonista (for a fantastic on device python interpreter with a number of libraries I use - numpy to be specific, Working Copy (for managing git repositories), Textastic (the most fantastic source code editor for iOS). With these apps in place my next quest was to see if I could manage even without the iPad around. This is my week 2 of the experiment and I think I haven’t faced a lot of issue for on the go programming. These tools just work great for me. Now I can pretty much keep my laptop at home and use the desktop at work, while on the move I just use my phone. There are a few things like join.me and teamviewer that may just work better on a bigger screen, but then I can also connect my phone using the lightning to vga dongle that I sometimes carry - if there is really this need.
Oh - and did I tell you that I wrote this post on the same phone ;)