I put together a script version of the full contents of the source build docs in the community portal here:
https://github.com/itiligent/Easy-OpenVAS-Builder
The script also adds a few extras such as grabbing the latest releases for each component (can be overridden) & setting up http redirect to https 443 with the built in GSAD web front end etc, TLS certificate mgmt etc. There is also an upgrader script in there.
Its Debian & Ubuntu specific but if there was interest I’d adapt it to RHEL too.