I would put the question back to you to answer.
Would you accept this offer on your house?
It all depends on the deal. Most of the sellers I work with would not accept this as written in your question. It's just too risky for them unless you are willing to put up a significant amount of option money that is non-refundable if you can't sell your house. They might consider if you have a contract on your home to sell fairly quickly and you can show them the contract and let them research the ability of the buyer of your house to close.
My advice to most buyers with a house to sell is to put yours on the market, get a contract. Once you get a contract ...then go shopping....unless you want and can pay for two houses for some period of time.