I don’t see any good options to repair this with the oil pan in place. I realize it is a lot of work to remove the oil pan, but that is your only option for a lasting repair. Once removed and cleaned, aluminum can be brazed with the correct type of brazing alloy and flux, using a MAPP gas torch.
If brazing is not up your alley, another option to repair the oil pan would be to clean it up properly, and patch it using a piece of thick sheet metal cut to the proper size with a hole drilled near each corner–but far enough from the corner, to provide adequate sealing area. I would get some black silicone and four bolts and four locknuts of the proper size. I would then place the sheet metal over the oil pan dry, use a permanent marker to mark the bolt holes, drill through the oil pan at the proper locations, apply plenty of black silicone to the metal patch, place it down on the oil pan, put the bolts facing into the pan, and the nuts on the inside of the pan, and tighten them, allow at least 24 hours for the sealant to cure, then clean the inside of the pan and reinstall.
Instead of silicone, an epoxy such as JB Weld could be used, which would be even stronger.
You might be wondering, could you drain the oil and patch the oil pan in-place using drill-point sheet metal screws which thread directly into the oil pan itself? The answer is no, because there would be no way to prevent metal shavings from getting inside the oil pan, which will ruin the engine bearings in short order. If this was a fuel tank, you could get away with such a thing, because the metal shavings would never make it past the inlet screen on the fuel pump. Even on a fuel tank, you would want to use fine-thread screws, not sheet metal screws in order to avoid loosening from vibrations.