One third of your wish is already answered. You can develop apps on the iPad.

How pray tell ... I was looking into doing that.

Swift Playgrounds

https://www.apple.com/swift/playgrounds/

This is pitched as an education tool...

> This is pitched as an education tool...

And? From the page:

> When you’re ready to share your completed app, you can submit it to App Store Connect right from your iPad or Mac with Swift Playgrounds.

Someone asked about developing apps on the iPad, this is a way to develop (and submit to the App Store) apps on the iPad.

Show me one serious iOS developer who's using an iPad as their primary dev machine.

I use blink[0] with a 40% keyboard to develop linux program on a vps.

If you want to do programming without wireless interenet, another option is to connect a raspberry pi zero 2w (with usb gadget mode enabled) to the usb c port using a single usb cable. Then the rpi zero will share a ethernet network with iOS device. Then you can use blink (again) to mosh to raspberrypi.local to do the development on the pi.

The reason that I don't do it on android with termux is that there's no high quality terminal emulator like blink on android.

[0]: https://blink.sh