Is LGPL-3.0-or-later compatible with Unlicense?
Yes.
Copyleft applies only to the copyleft-licensed files/library.
Result license is the more restrictive of the inputs. You must satisfy every input license's notice and source-offer terms. Verify pairwise compatibility first.
Resulting work's license: LGPL-3.0-or-later
General guidance, not legal advice.
Obligations when redistributing as open source
- LGPL-3.0-or-later: retain the copyright notice and license text.
- LGPL-3.0-or-later: state significant changes made to the code.
- LGPL-3.0-or-later: publish the source of any modifications to the library itself.
- LGPL-3.0-or-later: modifications to the library must remain under LGPL-3.0-or-later.
Other distribution models
The verdict is the same under every distribution model; the obligations differ.
Check this pair in the tool to switch models.