Tiki 28.0 will be released in October 2024.
It is a Standard Term Support (STS) version and will be supported until Tiki 29.1 is released as per the Tiki lifecycle policy
You can see the development page at : https://dev.tiki.org/Tiki28 and all the code commits here: https://gitlab.com/tikiwiki/tiki/-/commits/28.x/ once it will be created (in 2024-09).
We will stop offering ADOdb, as we have been using native PDO for well over a decade now.