Thanks for the help @rolandinho, @dbu
What I am hoping to find out is whether PostFinance would allow payout from its Vested Benefits plan (2 Pillar) up to 1 month before leaving CH.
The website link from @rolandinho seems to confirm what @jorgel shared: that this is possible for 3 pillar, which is great news - thanks! However it does not confirm for vested benefits, unless I missed something.
The background is in this thread. In summary if you move to certain countries e.g. Spain and withdraw a large 2 or 3P pot after the move you likely have to pay tax there (Spain >45% depending on the amount)