About ultra-massive block holes like this one or TON 618 which is even bigger, at 66 billion solar masses:
Since there are so, so big and it would take ages to travel to their centers from the event horizon itself , would it be possible to be inside the event horizon in orbit?
For how long, in theory (I imagine that orbit wouldn't be stable)?
Last but not least, would you be able to see the singularity from there?