not if you are going to use a machine washer! By hand? sure.
You can try hand washing it and using bath shower gel/soap. It is very delicate. It depends on your comforter.
soap is soap, would not use but few tea spoons. Its designed to foam up, two drops of good dish soap will wash a load of dishes in 2 gallons of water.
It would be fine it is just figuring out how much soap to add. I use 'Dawn plus bleach alternative' which actually has laundry instructions on it. Now it makes sense as to why.
If you only need to freshen it up you could put it in the dryer with a bounce sheet. I think it would be really hard to rinse the dish soap out of the comforter.
Yes, but it is hard to rinse it all out. Careful not to use too much. let the soap agitate in low water before adding the comforter and changing to high cycle. Run through a second rinse cycle if it feels soapy when done.