Managing WordPress instances in the long term sometimes is difficult. Especially when it comes to updating for a couple of plugins and themes. Doing it via UI is hard.
Basically your project idea simply has dependencies: WordPress, "Plugin A", "Plugin B" and "Theme C". And when it comes to dependencies, the WEB has proven there are better ways, then clicking through some backend UI.
This repository is for demonstration purpose. It's a basic WordPress with some official plugins and themes but also shows how to add some private stuff (e.g. paid plugins and custom implementations).
Since we now have a specific description for our dependencies, why not using CI/CD to build and deploy for each change?
There is a pipeline checking each monday 5am for available updates. If updates are found, a pull request will be created. For pull requests to master, the usual pipeline starts and runs several checks.