> In most cases they need to be able to issue a commercial invoice in a region compatible with company accounting.

The need for this invoice is because companies cannot justify irrational spending. The have no process for gift-giving. There is almost nothing that will make spending on OSS not irrational, unless you're paying for specific bugfixes or customization work. You can't issue an invoice for nothing. How much would the invoice be for?

edit: that being said, please continue to make up any pretense to get OSS contributors paid if that's working for anyone.