Why is hover bad for accessibility?
Additional content that appears and disappears in coordination with keyboard focus or pointer hover often leads to accessibility issues. Reasons for such issues include: the user may not have intended to trigger the interaction. the user may not know new content has appeared.
Should I hover or click Mega menu?
In conclusion, you should ask yourself whether your "mega menu" is an action or an interaction, and furthering that, whether it changes, adds, deletes or modifies the user's experience in any way. If the user will be initiating an action - use a click. If it is an interaction - use a hover.
What is menu hover?
The :hover selector is used to show the dropdown menu when the user moves the mouse over the dropdown button.