A living tree is nice if you can keep it alive (very difficult) but I don't know how eco friendly it is. The difference in fuel required to excavate and haul the root ball (total weight 100-150 kg), vs. hauling a cut tree (maybe 10 kg) and extracting a stump; the thousands of gallons of (usually potable) water that have to be fed to the sapling as it gets established, vs a much smaller amount of water to farm new seedlings each year...

Just speculating here, but I'd have to think that the main route to an eco friendly holiday season is the ordinary one of reduce and reuse. That all becomes so much more difficult under the commercial pressures of the holidays of course - which is all the more reason to try.