Ah 5V is not a big issue but another component needed… you could connect it to your 12V bus with a step down 5V. This would not be my recommendation, better to organize the 12V led
Anyways, now it is depending what the aim is of this push button. To have it illuminated all the time (not when pressing the button) think this could be a solution, just connect the led contacts parallel on the switch contacts. And using a VMB8PB(u)…
If you want to create some kind of quiz button when i lits after pressing the button, then you’ll need some more hardware assigned… so really depending on the installation itself to be honest, maybe an additional relay would be required.