I use on-screen keyboard Caribou in Gnome DE and switch the keyboard layout using Gnome Shell Extensinons "On-screen keyboard button" on top bar.
How open on-screen keyboard in Deepin when tablet no physical keyboard is attached? Deepin DE have nice icon menu for tablet Mac-Launchpad style, but virtual keyboard in Deepin without button keyboard cannot be opened.
Maybe add keyboard button in Deepin dock?