The free AI bookkeeper could already compare a sole proprietorship with an S corporation from the command line. It is now a button under the tax estimate card: it takes your books' annualised Schedule C profit, an owner salary (half the profit if you leave it blank) and a yearly running cost (the default is $1,500, an assumption you can change), and shows income tax, payroll or self-employment tax and the all-in difference. It also shows a salary sweep from 30% to 100% of profit and the break-even profit.
It is federal only, one owner, and a worksheet rather than tax advice. The salary has to be reasonable for the work, and states differ. Everything runs in your browser; your books never leave your machine.