They aren't a tool to identify fake news just an additional information layer which you either trust or xou don't.
>If your tools are poor, make better tools
If you are a bad painter buy better brushes.
You solution doesn't give the people the tools you still have just a source which claims to show what's true.
The real tool is the user himself using his brain. But that's hard to achive.
Most social media interactions about status plays, "buy my stuff" grifting, and - most of all - tribal identity politics and affirmations of belonging and identification.
With fake news there's also a fair amount of narcissistic contrarianism.
All of this passed through an online culture optimised for engagement through dopamine hits, rage, fear, and grudge farming, quick-hit entertainment, and other addictive mechanisms.
The real motivation in all of this is emotional self-soothing, not a desire for accurate facts.
So gluing "This isn't true" on any of that won't make a difference, because the problem is structural.
Fake News is a cultural and emotional exploit. It reflects cultural values, and it needs cultural and psychological defences.
Some options include better accountability for mainstream journalism; finding healthier income models that don't rely on addictions and ad tech; teaching media literacy in schools; and generally tidying up online media toxicity at all levels.