If the tooltip text is brief, the ARIA label can work well for users who are both navigating via keyboard and using a screen reader, such as people who are blind, low vision, or have a reading disability. However, users who rely on keyboard navigation and primarily perceive the page visually often aren't using assistive technology that communicates the ARIA label the way screen readers do. This can include users with disabilities related to motor function or chronic pain, and users who simply prefer to use keyboard navigation instead of a mouse or another pointer device.
A popular strategy is to ensure tooltips open on both mouse hover and keyboard focus, so a broader range of users will have access to the information regardless of the input device they are using.
To learn more about web accessibility considerations for keyboard navigation, explore the Keyboard Navigation & Focus Management course from Accessible Web Academy. If you are a web design agency and are not part of our accessibility for agencies partner program, let's talk!