ONLYOFFICE Desktop Editors v7.4 is already available, offering the majority of the improvements of ONLYOFFICE Docs v7.4. Read this post to find out more.
ONLYOFFICE Desktop Editors v7.4 released: form templates gallery, plugin manager, new print settings and more.
Didn’t try it but it looks like they also provide an installable offline version under the AGPL: https://github.com/ONLYOFFICE/DesktopEditors