Top-Level Await is being implemented, and will be ready for testing soon. This bug is for tracking the integration of this feature with devtools.
Example code can be found in the explainer: https://tc39.es/proposal-top-level-await/
And the test262 repo can also provide some files for testing: https://github.com/tc39/test262/pull/2274
I don't expect any changes to be necessary here, beyond maybe a few tests.