Has anyone had experience with adding PayPal as a payment option to the QuoteToSalesOrderWizard module? When the natural Checkout With PayPal functionality is enabled, the PayPal payment method is not an available option when creating a sales order from a quote in My Account. I'm curious if there is a specific reason for this, or if anyone has had experience adding it via a customization.

You won't be able to achieve this with the native paypal integration. The native paypal integration is coupled to the cart/Live Order commerce API methods. Meanwhile, the quote to order process doesn't use the cart/liveOrder. It uses suitescript to do nlapitransformrecord. You might investigate the alternative route. I'm not 100% sure, never done it, but seems something that can be PoC'd: Use a 3rd party implementation of the Paypal payment integration (with paypal as an "external payment"). This is offered by SoluPay.

Thank you, Pablo. I appreciate your insight. You've essentially confirmed what I was able to find in the source code: That this would be a relatively substantial customization.