What is the crowd's opinion of BORG Calendar?

From 3.5 billion comments

Nextcloud is the best alternative, but its not "download and run"

Lightning is really good, but it involves an email client (thunderbird)

Similarly if you have an old MsOffice suite license lying around, Outlook calendar (the old application based one, not the newer cloud one - which I undertsand you dont want) is very capable

If you want FOSS, and just a simple calendar app thats standalone, you might like Borg, which looks like its getting regular updates and still supported https://github.com/mikeberger/borg_calendar