hiring 1 agent or many agents at once to sell quickly

If you have little time and money left, will you choose to sell with 1 agent exclusively or hire many agents to sell (open listing) and why do you take that action ?

can agent still advertise if they get a non-exclusive listing ?

As an agent I would not take an open listing.
Why spend the time and money with no guarantees of a commission. When you hire one Great Broker you hire every possible agent that could potentially work for you plus you will be gettinp representation keeping you out of trouble.

The only thing you should do with many agents is to interview them to pick the one that will work the hardest to get your property sold. Generally an open listing isn’t worth while as no one works very hard on them. A good agent won’t even take one.