FOIA requests are the correct venue. But Congress itself cannot compel DOJ document releases. That is my point.
You are probably correct that Congress cannot legally force DOJ to produce documents.
What Congress can do is hold endless press conferences and interviews making all kinds of unsubstantiated claims and turn everything into a wild circus.
Then if they want they can hold endless investigations to make everything into a bigger circus.
If they got lucky some administration official will get caught lying etc etc etc....
Then a President might end up hiring a Special Prosecutor to investigate the perjury cases.
Sometimes what is legally valid is highly risky and dangerous as a practical strategy.