Thanks for the detailed answers. I seem to have missed the fact that the MT7688 has host-only USB. That probably makes the Omega2+ impractical for my project.

I was indeed inspired by these artices for the Pi Zero:
https://learn.adafruit.com/turning-your-raspberry-pi-zero-into-a-usb-gadget/overview
https://www.novaspirit.com/2016/10/18/raspberry-pi-zero-usb-dongle/

They use the DWC2 driver for device-mode usb on the BCM2835, which allows me to use "arbitrary protocol" USB as described at http://www.linux-usb.org/gadget/. I could even implement my own userspace USB drivers using GadgetFS.

I was hoping to get something similar in a smaller form factor with the Omega2+, which also includes wifi out of the box.

A microcontroller-based solution would be nice as well, I especially like their much faster "boot-up" times, but afaik (I'm not an expert on them) they would require reprogramming for every specific use case, whereas I can just ssh into a linux gadget and reconfigure it on the go as long as it's connected to a power bank.

My current best bet is a Pi Zero with some sort of wireless extension.

I would like to keep it as generic and tinkerable as possible. One day I might need a flash drive that I can also access wirelessly from my phone. Another day I may wish to share the host computer's internet connection with a few people at a party. A third day I may use it as a virtual keyboard to paste long passwords on a public machine or use my phone's mike on a computer that doesn't have one built in. Linux is flexible, usb is flexible, why shouldn't be I?

Thanks, 30 seconds sounds reasonable.

I would like to build a small usb device running Linux that I can plug into a host PC like a flash drive. A possible plan would be to use an Omega2+ board with a male usb connector and a few extra components packaged in a 3d printed enclosure.

1. Is the Omega2+ a right fit for this project?
2. What extra components do I need? (I'll have the same male usb connector for power and data transfer. I'd forgo the dock because even the smallest version is pretty large. If understand it right, I will need a 3.3V regulator. What else?)
3. How long does it take the Omega2+ to boot up?