Ask HN: Advice when patent app pending for similar product?

My team has been working on a software product in an established market for some time. We're marketing and iterating, and we are optimistic about hitting product/market fit. A US patent application for a similar product has come to light. The product is implemented quite differently based on the application, but the result looks similar to the end user. We fear the application's existence will reduce our ability to raise money and/or lead us to eventual bet-the-company litigation if granted. How practically difficult is it to prove design differences in a software patent context? We think we're clear technologically, but will the burden be on us to expose our code to a judge or adversary in litigation? Assuming the market is big enough, can we steer clear of the US without worry? Are we dead in the water from a VC perspective? As no counsel will likely give us an opinion that it's okay to proceed, we're asking, what do you think HN?

Any insight appreciated.