I'm trying to find an event/observer which will fire once an order is paid in Magento (2.2.8).
- checkout_onepage_controller_success_action - seems limited to frontend orders (ie not called for admin created orders)
- sales_order_invoice_pay / sales_order_invoice_register - don't seem to be called for PayPal Express
Ideally I want to try to get something fairly universal which will cover any orders paid. Even better if we knew it was only going to fire once (ie not on sales order save, but worst case can get an order field).