The way I would do it is to use the tool that I wrote to do things like that: execsql.py, available from PyPI.
With a tool like that, designed to run scripts from the command line, you can automate the process with a shell script or batch file, and launch it with the task scheduler.
You can try one of the DBMS independent JDBC based tools. As they are based on Java they run on any platform that supports Java including Linux.
And to my knowledge all of them support exporting data to Excel file.
All of them are free, DBeaver and DbVisualizer have a commercial version as well.
DBeaver (Free and commercial version)
DbVisualizer (Free ...
If you're open to using a scripting client instead of a GUI client, then you might look into execsql.py. It allows you to connect to multiple databases (one on startup, others with the CONNECT metacommand). You can then copy a table or view from one database to another with the COPY metacommand and write queries to combine the data as needed.