It depends on what you mean by “importing”.
- using the bibliography software directly
I don’t think it will work. You may however look for extensions
- transfer a DB into built-in DB
Needs some programming which probably can be done with Base, but I doubt that all fields have a 1:1 mapping
- display using the same rules (format)
Most rules can be implemented by customising the Structure line generating the entries, but don’t expect 100%
Zotero/Writer are managed by independent teams.
LO tries to offer maximum flexibility to its users and they have a lot of work to fix known bugs on existing functionality. So, let’s not scatter their effort by requesting new features.
Zotero is not linked to any office suite and this is were the product has a weakness. In order for it to be “universal”, it does not use native features when it comes to insert a citation (because Zotero does not handle only bibliography entries). It uses macros to generate the insertions, formatting them with direct formatting (because it is available in all suites), letting the suite transform this into native encoding. This means you don’t control the look with styles (and they are ineffective because direct formatting takes precedence). If you add your own direct formatting over Zotero, on next macros activation it will be replaced by Zotero one.
I think both products are mature but the purposes are different and integration very difficult without sacrificing some of the objectives, notably “universality” or portability.