I need container queries!

Have you considered another design aspect that doesn't require queries?
No: Try this first, there may be a manner in which you can solve the same problem without needing any container query approach.
Yes: Move onto the next item
Is the container you're querying always a specific percentage to the viewport?
Yes: Then use a media query
No: Move on to the next item
Does the query depend on its child's size?
No: Move on to the next item
Yes: Move to this item
Does your container need access to the parent document (eg: access to CSS custom properties within that document)?
No: Use an iframe
Yes: Move on to the next item
Will your query change layout
No: Move to the this item
Yes: Try to use modern layout such as Grid or Flexbox
Did the modern layout work?
No: Move to the next item
Yes: Sweet!
Is the scenario primarily impacted by content overflowing?
Yes: Then use the IntersectionObserver technique
No: Then use resizeObserver