The most I ever made with Tcl/tk was a Message of the Day popup when I was the lab admin at my University. I think I lost the code for it though. I still use this ancient TCL script for keeping track of media I download.

https://battlepenguin.com/tech/scripts/lnsponge/

BigIP by F5 uses TCL for its rules/config (or it did at one time), but everything was namespaces and it looked insanely complex.