You shouldn't need to use any of the Arch stuff on Steam OS. It had a read-only root, so you'd need to disable that to use any pacman commands anyway.

You should be able to get everything you need through the Discover store, since most applications are available through flatpak. That should be a similar experience as any other app store, provided you know what you're looking for.

The main issues imo have nothing to do with Linux, but the form factor:

• screen to small to use for reading text
• no keyboard, so that needs to be brought separately
• doesn't stand up on its own, so you'd need a stand
• awkward shape for fitting into a bag with other stuff

If you're always plugging it into the dock, I'm not sure why you wouldn't just get a desktop or something and keep your data on a USB drive or in the cloud. If you use it even occasionally as a mobile computing device on battery, just get a laptop, that's what they're designed for.