Hello Mindaugas, I have to say it was very hard to understand what you were trying to suggest but I appreciate that you have tried to help.
I believe what you mean is going to General Settings and search on the search bar for "Invoicing Policy" (This will be under the "Sales" module tab) https://www.odoo.com/documentation/15.0/applications/sales/sales/invoicing/invoicing_policy.html
Maybe I did not do a good job at explaining the issue because it seems you have misunderstood the problem, because the solution you propose does not solve or correspond to the issue that I raised.

Your suggestion makes it that the Invoice is only created after the Delivery Order is done. What I need is the opposite, that the Delivery order is only created when the Invoice is paid. :)

https://www.odoo.com/documentation/15.0/applications/sales/sales/send_quotations/get_paid_to_validate.html

You could possibly use PoS App by enabling 'Ship Later' functionality or maybe even ecommerce App if your customers are able to create orders themselves.

make product invoicing policy-invoice ordered. after so confirmed. picking is ready. but first generate invoice after that picking.