My bravery was limited to adding it only now at the "Planning Delivery" stage. I've been reassured multiple times by Michael that adding the tow bar now should NOT delay delivery beyond the +1-2 days it might take for the local shop to install it.
That will certainly be one of the first things I bring up when (if?) I eventually get contacted by Polestar to coordinate financials, delivery, etc.
Just got off the phone to a Volvo dealer and they said they could fit a Volvo semi-electric tow bar at any time for just over £1100. They could also do the roof bars for £220, that’s £30 cheaper than through Polestar.