I have Arch (KDE) installed on my desktop at home. I have been using it for 6 years and I love it, especially the AUR!
This month I have been mostly using my laptop and I am using MX Linux 23 KDE which is great! I really find it's tools very useful when I need them (which is not often, but I am glad they are there).
I too use Arch on my desktop (on a daily basis).
I think you will find MX Linux to be a great fit for your secondary device. It works like a charm on my laptop.
What about library thing? I think it's also a good alternative to goodread.