It’s more GTD than kanban, but I’ve been getting a lot of mileage out of this stack:

- radicale as a caldav server with calendars per context, like @Writing, @Chores (https://radicale.org/v3.html)

- todoman for cli tasks (https://github.com/pimutils/todoman)

- iOS reminders for mobile

Everything syncs, and because it’s standards based it’s portable if a little clunky.

There’s also Vikunja, but I didn’t like it as much when I tried it last year. https://vikunja.io/