You have this flipped. Expense management systems with embedded company cards are an order of magnitude easier to managed and reconcile than dealing with thousands of employees' personal expenses and payouts
It's better to start early than anything, a lot of these certs are easier to get when you have nothing to audit. I've worked for 2 successful B2B fintechs, I wouldn't wait until a customer asks, I would be proactive if you have the time and money to go through it.