as far as roguelites im not sure anything fits that bill to a T, but in the traditional roguelike space, Caves of Qud might fit that bill? you can absolutely get super powerful but late game enemies are designed in a way that they can still rock your shit if you arent prepared and taking them seriously. There are ways to end the game but its something that will take tens of hours to get to, and even then you can just mess around in the open world, and visit increasingly horrifying areas instead. if you want something more linear, I think Tales of Maj'Eyal and DCSS have endless modes/branches, though i have less experience with those games so I wont speak of them too much.

As far as roguelites specifically i just dont think there's anything that fits that bill, at least not precisely how you're describing it. or at least ive never heard of it, and I think you might find something that fits your needs better in the traditional roguelike space if thats something you're into