I'm so sorry for your news. Getting a palliative diagnosis or just generally having a pig who you know is nearing their time is really hard, you start to do preparatory grieving even while they are still here. My advice- lots of treats. Lots of cuddles. Do a photo shoot and get a bunch of nice pictures. Just generally make every day as happy as it possibly can be.
Last summer, my 5-year-old pig, Leela, was diagnosed with an abdominal mass and we were told she didn't have a lot of time. We gave her all the lettuce she could eat every evening, cuddled with her a lot, and took a bunch of beautiful pics on her enjoying her time out on the lawn eating the grass. She actually surprised the vet and lived much longer than expected (about 9 or 10 months post diagnosis of her mass) and although I miss her a lot, it makes me feel better knowing that her last months were the best they could possibly be! Pigs don't understand their own mortality, so from her perspective one day the humans just decided to spoil her excessively every single day and she had many happy days with no clue why we were making such a fuss. Just make the days special and enjoy each and every one with Goma. He won't know anything other than he is loved and getting lots of time and treats from his people. ((HUGS)) to you.