Once everything is unpacked, are the resulting compiler materials sufficient to compile and run those packing and unpacking programs?
So, you need a minimal C compiler that can also compile the ungz and untar programs from their C sources. At the moment, I have a minimal C compiler that can compile the Tiny C Compiler and the standard library that is part of the GNU Mes compiler. One of the following tasks will be to see if it can also compile the sources for ungz and untar, which can be found in [0]. I think it will be not so hard as these sources already have been adapted to be compiled with a minimal C compiler.