There are some options that require some technical skills. I've seen other people in the community use the Export Canvas details to pull all the details of the canvas that are relevant to create an overview for QA. Braze has Approval workflows that can help if you have permission groups configured (which you plan on doing). Braze Teams can also be useful in creating certain default filters (e.g. Team US has a country = US filter applied to everything).
In terms of a Datadog alters, you can leverage the Export Canvas data summary analytics or Export Canvas data series analytics endpoints + connected content and webhooks to fire an API triggered campaign (to Slack or an email to a shared inbox) to create an alert. Another options to use Currents data to build some sort of alerting mechanism.
Overall, it all comes down to process and building good habits. From my experience, peer reviews are more useful than QA checklists for complex campaigns. Different QA checklist for different phases (HTML/content, campaign audience review, campaign overview).
Hope this helps!