error opening quartus or compiling opencl files as This is happening with Quartus 19.1. Any env variable I am missing? quartus: error while loading shared libraries: libxerces-c-3.2.so: cannot open shared object file: No such file or directory

You can try the following:

cd ~/opt
wget http://apache.forsale.plus//xerces/c/3/sources/xerces-c-3.2.0.tar.gz
tar -xzvf xerces-c-3.2.0.tar.gz
mkdir -p xerces-c-3.2.0-build
cd xerces-c-3.2.0-build
cmake -DCMAKE_INSTALL_PREFIX=~/opt ../xerces-c-3.2.0
make
make install

Or just try installing the package for Fedora and see if it helps. This should not cause issues as this package is mostly used by Quartus alone.