I would like to make a Database editable with LibreOffice Base and usable with python. I can't find a way with the normal HSQLDB as it requires Java (I would as less as possible dependencies) and the same thing with SQLite3 as it requires the drivers for LibreOffice.
Be sure to use a split database setup, rather than the default embedded setup. Otherwise it will crash a lot.
One solution that does not require Java is to switch to a different DB engine, for example MySQL. With this setup, see How do I connect to a MySQL Database in Python? LibreOffice Base works well with MySQL.
See also https://wiki.openoffice.org/wiki/FAQ_(Base)#Do_I_need_Java_to_use_Base.3F. Split databases are discussed on that page as well.