It does, but I'm not sure if I manually installed the official driver via copy and pasting the files in the right directory. I didn't manage to get the official printer driver working, but for the scanner I didn't really know if its due the official driver that it was discovered, or by the pre-installed ones.
I installed simple scan and when I click preferences I could select it under the scanning sources
At least the archwiki tells me that most of the scanners should work out of the box
https://wiki.archlinux.org/index.php/SANE
scanimage -L should list the scanner sources in the terminal. If your device appears with this command you should be able to select it in sane too.

I have a canon mg6450 and I got it working via lan and postscript.
If you use the printer on your lan, maybe that works for you too.
For usb I have no idea atm, since it is not connected to my computer directly

Thanks

It is already installed on my system. I reinstalled it and tried again, but it still has the same error.

Thats right, but the app should bring its own.
In terms of security it also shouldn't be a problem, because the default access can be restricted to localhost only.
I don't know how the included qt ui looks, but worst case pyload can be used as a chrome app (add to desktop functionality) and pinned to the taskbar.
Besides jdownloader which already was turned down in the repos, because there was no proper source, this is the only viable app that I've found with the same kind of functionality.

I played around a bit and kinda got it working.
Can anyone try this:

ups...sry, I wonder how I've missed that.

What about https://gufw.org/ ?
It's a gtk frontend for ufw.

Pyload is manly for one-click hoster (share-online, uploaded, etc...)
It has support for RSDF/CCF/DLC containers, automatic captcha recognition etc.
and ClickNLoad support. Basically everything that jdownloader does.

I also have the problem that I can't play any videos from my nas, neither with vlc nor smplayer
(My smb share has credentials btw)