Yes. You can just get by with 2 devices but you need to set expected_votes=1 in the cluster config somewhere, don't recall where, and I've encountered issues with stability with that solution, seems like it'll get undone though I haven't used it for years to say if that's still the case.
The q-device will work on anything Linux that's available when the second node is down. Not having the tie-breaker isn't the end of the world, it just means you have to go in after you bring up the second node and start some things manually, and if you're replacing nodes in a 2-node cluster, it's much nicer to have the q-device.
