A Dyson sphere around a black hole

I've wondered if somebody could use a black hole jet to power a civilization. The trouble I see with it is that the power of the jet is highly variable so you need some mechanism to even it out... Maybe some really big dust clouds that re-radiate it at a reasonable temperature.

Meanwhile, we can barely get scramjets to work on Earth. I'd say this idea (which is a bit vague to me) is pretty far off.

I think it's interesting to work the problem through backwards.

Imagine that a population was settled in some situation like

https://arxiv.org/abs/2011.07487

and they were interested in visiting the Earth after 1000 years of not doing so. Alternately imagine some species with an interstellar lifestyle based on oort cloud objects and D + D fusion wanting to do the same.

They could have highly developed technology in many respects but they might find the process of developing a "space shuttle" that can enter the Earth's atmosphere with a full load of fuel, then SSTO back to space to be difficult.

Even an interstellar-capable civilization might take as long to develop an excursion vehicle for the Earth as it took us to develop a vehicle capable of leaving the Earth.

Notably the Earth is a lot harder to get on and get off of than other worlds; the 2nd stage of the SpaceX Starship can SSTO any world in our solar system which could plausibly be landed on except for the Earth.

Interstellar voyagers who had spent 10,000 years en route would inplausibly have one ready to go, the best they would have is 10,000 year old instructions to make one with a 10,000 year old 3-d printer. (Which got optimized to make fusion reactor parts and might not quite make reentry body parts exactly the same as it did the last time it made them.)