In MS Office I could create a database of addresses etc and then use mail merge in MS Word to create letters, envelopes, and what they call a directory which is basically a listing extracted from the database. However it seems that LibreOffice only offers merge for letters and emails whereas I need the envelopes and directory features as well.
LibreOffice doesn’t limit you how you place mail merge fields on the document. You can use them to create envelopes as well (there might not be a pre-made template, though).
Wrt “what they call a directory” - it would be better if you provide a link to documentation on the feature, to understand what are you talking about, and be able to answer if this is possible with LibreOffice.