Project based but on-site for like one or two hours. Something where they consume a public api and build a UI usually a list on it. Will allow you to see their dev setup, etc... This will give you by far the most signals.
Discussions around state management, js libraries (react, vue, etc...), testing strategies (storybook, etc...) should also give you some signals too on their experience.
I think Twitter should allow trusted/editorial account that shows prominently (even part of the tweet itself) on world leaders tweets.
This will be NYTs, Washington Post, etc... of the world.
The big plus here is we return the editorial part of these institutions. Imo, these used to be net positive on the society (see Watergate during Nixon)
Twitter will pick the list of editors (kind of what they currently do with the verified account) The bar to be an editor needs to be high and a trusted source of news.