grab wont help u, there is a group dedicated for grab driver and ask people to avoid traffic jam, they already know bukit jalil going to have traffic and they wont go near or even try to cancel it

my advice is go there in early morning 5-6am by car and park there whole day, i am not sure what is your concert but there is lrt train nearby in case if u want go shopping.

yes i been to miku concert before.

train close at 11:30pm, my advice would be go to the lrt by 10:30 for safely reach home.