Zim really is amazing, its the perfect balance with its simple plain text files in folders data structure, but powerful search and back linking. And I love linking to other files on the local file system.
How do you do the LUKS volume upload to cloud? Is it for syncing between devices or just backup? Personally I use (self hosted) NextCloud to sync my Zim between devices.
OnlyOffice is also available as a (offline) desktop office suite, so as a user it’s more like LibreOffice than Collabora.
My wife prefers OnlyOffice over LibreOffice, as it’s feels closer to MS Office. Also it’s compatibility with MS Office formats is better than LibreOffice.
I still use LibreOffice for desktop, but I’m not a heavy user. Haven’t tried out Collabora or hosted OnlyOffice for NextCloud yet.