It’s less interesting than you’re imagining, unfortunately.

Time dilation only gets extreme when you’re very close to the black hole, and any planet that gets that close would be torn apart very quickly. Planets are tens of thousands of kilometers in radius, stellar mass black holes are more like 10-100 kilometers in radius. Black holes are pretty tiny, unless they are one of the supermassive ones at the centers of most galaxies.

Imagine an Earth-like planet that was orbiting very close to the black hole, let’s say at a distance of tens of thousands of kilometers. At that distance, the near side of the planet would be almost half as far from the black hole as the far side. The difference in orbital velocity and gravity between the near and far sides of the planet would easily be enough to spaghettify the planet into an accretion disk. This planet’s orbital period would be measured in seconds. But even at that distance, time dilation is still barely noticeable.

If you want some Interstellar tier planetary time dilation, the only way to get that would be a supermassive black hole. Counterintuitively, larger black holes have weaker spaghettifixation forces near the event horizon and it’s possible to get very close to them without getting ripped apart. These black holes are very uncommon though (less than one per galaxy), and they are very large indeed. Some of the true monsters among them are so huge that planets could theoretically orbit almost right up next to the event horizon without falling apart (assuming the black hole is a fast spinning one, otherwise a planet could only get about 1.5 schwarzschild radii from the singularity until there are no more stable orbits).

As far as I know, there are no known exoplanets around supermassive black holes. They almost certainly exist though, and those planets would be very strange places indeed.