This page explains how to make chromium usable in mobile UIs like plasma-mobile.
Install chromium package from alpine.
Configure startup (scale + useragent)
Edit /usr/share/applications/chromium.desktop and set the following line:
Exec= GDK_SCALE=3 chromium-browser %U --start-maximized --user-agent="Mozilla/5.0 (Linux; Android 4.4.2; Nexus 5 Build/KOT49H) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1700.99 Mobile Safari/537.36"
You may adapt scale and useragent to your needs.
Currently on-screen keyboard does not work with plasma-mobile (see ). You may install this extension to get a virtual keyboard nevertheless (though it does not work with every website):