Ubuntu Touch and installing .click packages outside of Ubuntu app store?

I have just gotten my hands on an E5 Ubuntu Touch device, however, I don't want to register anywhere (including the Ubuntu app store) until I get the hang of it.

Now, I'm aware that on Android, the app store packages have an extension .apk, and they can be installed either through the Google Play store with a proper login, or through a USB connection using adb install *.apk.

I've learned that on Ubuntu, the format defined for Ubuntu Touch is called "Click," using the .click file extension, and it can also be installed either through the Ubuntu app store, or through a USB connection using pkcon install-local --allow-untrusted *.click.

However, I'm also aware that on Android, you can start a download of an .apk file, and then install it by doubleclicking (or its equivalent in tapping) once its downloaded; can Ubuntu Touch do the same?

If it can, is there an example online of a very simple .click application, that I could download and install the same way - possibly by allowing some developer options first?

I've noticed via Touch/Collection - Ubuntu Wiki, say, the xkcd-viewer app - but all it offers for download are .deb files, which apparently don't install on Ubuntu Touch, at least not through the GUI.