Back in the days before git, I worked on a small software+hardware startup with ~ 10 people. We used Trac very successfully to do project management. I know it’s been updated to mesh with git. You could set up roadmaps, track issues (which can be linked to code or not), tracked hours (using a plugin), and keep our internal KB in the integrated Wiki. There was a Trac Hack for everything we wanted.

I don’t recall which Gantt plugin we used, but there’s a few options: trac-hacks.org/tags/gantt

We didn’t use kanban back then, again, options: trac-hacks.org/tags/kanban