All parts of a page must be keyboard accessible, including dropdown navigation. I check Dawn theme and some top theme on shopify theme store, but the dropdown menu does not work with my keyboard navigation, please explain me about this requirement
Hello @aliepenter ,
Greetings from the Store Watchers Support Team! Happy to help you today.
I tested keyboard accessible on the Dawn theme navigation menu and I was able to access the navigation with keyboard.
To open the dropdown navigate to the dropdown (using Tab) and press Enter.
Let me know if need further assistance 
Regards,
Store Watchers Support Team