When notifications or status messages are part of your app, first check for the following.
Does these messages auto disappear?
Can the accessibility service able to identify and announce the message when it is displayed?
Are these notifications or messages consistently displayed in the same location on the screen each time they are displayed?
Depending on the answers you get for the questions above do the following.
If the notifications or status messages disappear automatically, ensure that the messages are displayed for longer time. Depending on the characters the message holds the time should be changed.
Using aria-live property convey the message in the notification or status message to the accessibility services such as talkback or voiceover.
Notifications such as android toast messages can be displayed anywhere on the screen. Making the display location consistent can benefit low vision and cognitive users. Eg: If the notification is displayed is located on the top right corner, consistently display any other notification through-out the app in the same location.
WCAG Success Criteria
4.1.3 Status Messages (Level AA) WCAG 2.1