As a noob I’ll try to add my two cents too.
To get online, we are doing it over TCP/IP protocol - via networking. Since this is not secure by any means, Qubes devs disabled networking for dom0 and templates and invented new, secure protocol - qrexec primarily for templates (and dom0).
Think of it as a proxy, which it actually is. So you are getting stuff from online and not being online out of the box. Great, isn’t it?
Well, there’s a catch. Access to online stuff out of the box is limited only to default official distro repositories - for obvious security reasons. So, no signal, vivavldi, chromium packages if they can’t be found in official repositories.
But, the devs didn’t leave us alone on this. Since qrexec is a proxy, it is actually possible to get other stuff online once you learn that this proxy actually runs on 127.0.0.1 via port 8082 (you’ll later learn where)!
So, if you are sure and you trust third-party repositories, the only thing you should do is to add this proxy address to the download link and voila!
So, your commands should start with:
wget --proxy http://127.0.0.1:8082/ address-of-a-key-to-import or whatever
Or, if you are experienced enough, and aware enough of the risks, then you probably already got the picture that you can create a simple file ~/.wgetrc in a template:
use_proxy = on
http_proxy = 127.0.0.1:8082
https_proxy = 127.0.0.1:8082
and everything should work now out of a box.
Remember, qrexec is powerful tool, and using it carelessly could lead you to unimaginable consequences you probably wanted to avoid by starting to use Qubes, actually.
For me, key word for Qubes became qrexec.
Does anything of this make sense?