tcl-itcl4 binary package in Ubuntu Focal armhf

 [incr Tcl] (or itcl) is a popular object-oriented extension for the
 embeddable Tcl scripting language. The name is a play on C++, and
 itcl has a similar object model, including multiple inheritance and
 public and private classes and variables. Unlike most OOP extensions
 to Tcl, itcl is written in C for speed.
 .
 This package contains everything you need to run itcl scripts and
 itcl-enabled apps.

Source package