WASHINGTON—The long-awaited nearly $900 billion U.S. pandemic aid package will help banks by boosting borrowers’ finances, easing a key small-business lending program’s rules and by granting accounting relief on deferred loan payments, lobbyists and analysts said. After months of partisan wrangling, the U.S. Congress over the weekend struck a deal on another pandemic aid package, including one-time $600 checks for most Americans, extended unemployment benefits of $300 per week, and $284 billion more for the small business Paycheck Protection Program, or PPP. Passed by lawmakers Monday night, the package includes a number of measures that the industry, potentially facing more than $300 billion in losses on souring loans through 2022, according to consultancy Deloitte, had lobbied for aggressively to bolster their books and help their customers. Those efforts extended through the weekend, with industry lobbyists making last-ditch calls to lawmakers to push for their asks in the final text, lobbyists …