You all wait for Plone 5.2 to finally be released. But there is still a blocker that needs to be fixed first and we could really need some help:
Registering allowed_attributes and allowed_interface in BrowserViews is broken in Zope 4. See https://github.com/zopefoundation/Zope/issues/397 and the discussion in https://github.com/zopefoundation/Zope/pull/610. That's a tough one resulting from a mayor refactoring of BrowserView in Products.Five dating back to 2012.
This feature is used very rarely in Plone but break least two features: Stealing locks for locked items and enabling ical-import for folders.
The question is: Can we fix this or should we release knowing (at least) these two features are broken?