I can use any package manager then can I?

I am on a old machine and compiling everything is not an option.

Since there is a “decoy” historical filesystem to adapt to other Linux program, can’t I just use any package manager I like and then run SymlinkProgram ?

No, you can only symlink programs installed in the right place, which other package managers won’t do (i.e. it’s a one-way process to create the symlink tree). You may be able to use the ThirdPartyInstaller tool to extract Debian or RPM packages into the right place, though it won’t always work out.