Anything that is not your own will never be enough. We PHP devs are stubborn and like what we like.
I honestly believe you should build your own framework/base template with SlimPHP as a starting point, since you appear to be more experienced with it. Add in a couple endpoints which (safely) expose the git HEAD, phpinfo, and logs.
It wouldn't be too difficult to make a separate dashboard that inspects those endpoints periodically for all your sites. (Or integrate with the WordPress REST API.)
Essentially you would be laying the foundation for Command and Control.
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