Traditionally on XFCE you would have a menu button and window buttons in the panel. You could create a launcher for an application in the form of an icon, and have window buttons in the form of icons for running applications. With the obvious disadvantage that you would have two application icons on the panel, where really you only need one (taskbars can contain a pinned launcher which, when the application is running, can also be used to switch to the application).
There is now such a taskbar available for XFCE, called xfce-docklike-plugin. It's not in the Debian Bullseye repository, so it's necessary to download, build and install it.
Unless you cheat and use the MX Linux repository based on Debian Bullseye. MX Linux XFCE edition is using the plugin as it's default window switcher. The repository is here. Tested on Debian Live XFCE non-free. You will need to install
xfce-dev-tools
