Wacom tablets, including digitisers in screens, should be supported out-of-the-box with Linux.

I have a dual screen setup and a Wacom tablet. As one screen is 4K UHD and the other FHD, this is too much screen estate for my shaky hand on the tiny Wacom tablet that I have (the tablet has 2540 lpi resolution, so this is not a restriction of the tablet, but the blame goes to me). Therefore, I want to restrict the tablet use to the FHD screen only in order to get a more calm pen usage.

On my Debian KDE system, this can be done by two means:

• Install the KDE Wacom configuration tool via Debian package kde-config-tablet. In that tool, either set the mapping of the Wacom tablet to a specific screen (do not forget: you need to click "OK" also on the initial overview screen, i.e. end the whole setting process). Or use the pre-defined keyboard shortcuts to set a tablet-screen mapping.
• Use the command line tool xsetwacom: get the screen name via xrandr (e.g. eDP for my laptop screen) and, get the name of the Wacom tablet via xsetwacom --list. Note that multiple entries are listed there for the same tablet: take care to use the one that ends with stylus. In my case, I use
  xsetwacom set "Wacom Intuos S Pen stylus" MapToOutput eDP

In online teaching, I enjoy using to draw on slides. E.g. for drawing on PDFs, I use either KDEs okular PDF viewer (in presentation mode, move to the upper screen edge to get a menu with pen colors) or xournal or rather it's fork xournal++/xournalpp. While I run PowerPoint on Linux with Wine, exactly the presentation mode drawing function does not work (I see the dot representing where the pen would draw, but drawing does not leave a trace).

For using the pen in Gimp, it is important to understand that the Gimp drawing tool that shall to be mapped to the pen needs to be selected from the Toolbox window with the pen itself! (The pen and the mouse have different tools associated and Gimp distinguishes this based on what input device is used to selected the tool. Trying to select the tool with the mouse and then using the pen will only lead to making the pen crop (which is probably the default behaviour): this mode is also displayed at the bottom: "click-drag to draw a crop rectangle".)