There is absolutely no need to even involve chroots or anything that needs special privilege just to run a compiler. Typically, a compiler will just read and write files. This is how it ought to work.
1. Download gcc-8.x.y.tar.xz
2. Untar anywhere. I like to do this within my home directory.
3. Run ~/stuff/gcc-8.x.y/bin/gcc
If this simplest possible thing does not work and drives you to Docker or chroots or similar things, then something fundamental is broken.
