I am pretty sure that the crew have access to a cockscrew on board (another security item issue) and are happy to open your duty free bottle for you.

Have not flown recently but I do recall a band who were famous in the 70s flying to do shows in Brunei in the early 90s. The brought their own booze in SIN duty free with a top-up purchase in Dubai/Abu Dhabi during the stop-over.

Not sure about FA serving it to you. They will let you have glasses and let you borrow the cockscrew; or the may even open the bottle for you.