Test on one device of your choice. (can be tested on browser)
Test login with sitefinder works.
Change config.json multisitesdisplay to url
Check you can login without site finder entering a url.
Change config.json multisitesdisplay to select and add some siteurl as well.
Check you can login selecting a site.
Change config.json multisitesdisplay to buttons or list and add some siteurl as well.
Check you can login selecting a site.