This device test from January says screen readers mostly do not announce <abbr title=>s, except for Android/Chrome/Talkback that only announces the title, and then a couple that might when using virtual cursor.
The title is also not exposed in Braille displays, and can’t be accessed by keyboard or touchscreen (for example, mobile phone) users.
The verdict starts:
Don’t use
<abbr>with or withouttitle. Exposure continues to be inconsistent across browsers and assistive technologies. Some set of users will always miss some piece of information.