In the investment world and with rehab flip projects, I often make offers prior to having my financing “locked in”, however, an important distinction here is that I have a large private investor network I have built over the years with $10M+ available to me so I know that when I have a deal, the money is there, just not officially approved yet.
If you are new, don’t have that kind of capital in the background, then you would be taking a risk entering escrow without your funding in place. You can always get a quick approval for a hard money loan but you will need capital in your bank to cover down payment, closing costs, perhaps rehab costs (some lenders will lend rehab funds too), and carrying costs like taxes, insurance, utilities, and interest payments.