There is a plugin that does this but I stopped maintaining it because certbot is a moving target and the version in the Debian repo is rarely up to date enough for a lot of people. The wildcard feature that most people want is very difficult to automate as well.
And yes, I do tell people to use docker. I use certbot myself. Putting it in docker doesn't change that much. It actually makes it easier if the system you are generating the cert on does not have a web server or you do not want the current web server exposed to the internet (like OMV's web server).
I can totally understand that. I personnaly recompile the latest versions of handbrake, qbittorrent-nox to be up to date in debian 10, and this can be a real pain
Certificates are much more used and useful. As said just before, maybe a path to the automated certificat in the Certificates or General Settings tabs in OMV could be a huge help for a lot of people ?