re.
<code bash>
# switch to root
su -
# install openmpi and python3-numpy; petsc requires python3-numpy and OpenBLAS;
# build queuefiles, not packages, to automat... ically build any other dependencies
sbopkg -k -i "openmpi python3-numpy OpenBLAS"
# download and unzip a petsc build script
cd /tmp
wget https://clawiki.isne