Will there be the ability to connect with a SQLite database on the xojo server using a local desktop client?
No, but you can’t really do that with any server accessed via the web. AFAIK there are no desktop clients that can do that via a web connection. You can sometimes fake it where it will download a copy (via FTP) of the data and when you change a value it uploads the file back up and replaces the existing file.
There are some options though. A) You can download/upload the SQLite file as needed to your desktop. B) Create a Web App that mimics what you need to do.