How to sync lighting Calendars

Hello,

My wife and I both use Icedove. Her on her computer and mine on mine. Two different email addresses.

We both use Lighting Calendar extension on IceDove.

Is there a way that does *not* involve cloud SaaS whereby we can sync each other's events so that we can share a Calendar?

Ideally this would be seamless, but worst case scenario we could export our calendar's, encrypt them, email them to each other and import, but that would be a drag, but acceptable. Instructions for this method would also be a help if the seamless way does not exist.

Thank you in advance!