KDE Connect with Thunar?

Lack of integration is simple to resolve:

xfce:xfce4-settings:preferred-apps [Xfce Docs]

Others

A Multipurpose Internet Mail Extension (MIME) type identifies the format of a file. The MIME type enables applications to read the file. For example, a file manager can use the image/png MIME type to detect that a Portable Networks Graphic (PNG) should be opened with Ristretto.

With the MIME Type Editor application, you can view and modify the Default Application that is associated with a Type.