This exactly. You never know what it will do. Will it simply check that you have Python and virtualenv and install everything into a single directory? Or will it hijack your system by adding trusted remote software repositories? Will it create new users? Open network ports? Install an old version of Java it needs? Replace system binaries for “better” ones? Install Docker?

Operating systems already have standard ways of distributing software to end users. Use it! Sure maybe it takes you a little extra time to do a one off task of adding the ability to build Debian packages, RPM, etc. but at least your software will coexist nicely with everything else. Or if your software is such a prima-donna that it needs its own OS image, package it in a Docker container. But really, just stop trying to reinvent the wheel (literally).