In the past I had a Acorn Archimes and therefore I am interested in what to do today with a ARM processor. Are the devices like Raspberry Pi 3, Odroid C2, Pinebook or Rock64 more for experiments or will there be the possibilty to build a whole Desktop PC around them? How to connect a SATA device, a keyboard, a mice etc. to them. Are there Shops which sell whole Systems?
I can only speak for myself.
The raspberry Pi 3 is best suited for something like a media server. It's limited ressources make it terrible at desktop computing.
The Odroid-C2 is the same, just with better hardware.
The Pinebook I use for everyday stuff, like web browsing, email, SSH etc.
The Rock64 is a beast compared to the other. The 4 GB RAM makes it an ideal candidate for desktop use.
To connect a sata device, I would get a USB3 -> Sata adapter (they can be bought at pine64.org).
Keyboard and mouse is just a standard USB plug, which these devices have multiple off.
As far as I know, ARM boards can not be bought as a "whole system".
But you can buy, the board, power adapter, case and periphials in the same shops, so you can essentially buy a whole system.
I use a Raspberry Pi B+ (of the first generation), however, not with Manjaro ARM but with Raspbian, since Manjaro ARM does not support the old architecture, afaik.
It's really slow, actually. I only access it via SSH, so no GUI is running. It serves as an NFS server (central file storage, a 250GB external HDD is connected for this purpose), torrent client (put the Manjaro ISOs there, when torrent downloads were still possible, I fear, they aren't any more for newer ISOs...) and CUPS server (for sharing a printer in the local network). I once set up Owncloud on the Raspi but it was rather slow due to my limited upload bandwidth, and in particular slow for a large number of small files due to the Raspi being slow and some Owncloud bug, so I stopped using it.
My Raspberry Pi 3 runs my Nextcloud
Works well, although today there are probably even more suitable SBCs with decent support available .
I'm just now getting back into the game but the odroid-c2 is great for servers. I've had a nextcloud, nfs media share for streaming to another SBC, and several virtual hosts running on mine for nearly 2 years without issue.
I also have an old beaglebone black being used as a 'pihole'
Raspberry pi2 as an HTPC (it isn't so great at this. Will be replaced soon)
Another odroid-c2 in my vehicle as a carputer
Beagleboard-xM as a microcontroller test apparatus for some school engineering project
And finally sitting on the desk for testing is rockpro64 and odroid-n2
We are just now getting to this stage. As these things get loaded with more and more power, people are starting to look at them for basic computer replacements. @PINE64 is a company that has taken this and made a laptop (Pinebook) based off of one of their boards and are working on a more powerful one (Pinebook Pro) . It's interesting to see the evolution of these boards.