Hi Chingis. There is no PowerApps & Flow licenses included with SharePoint 2019. PowerApps and MS Flow are also not part of SharePoint 2019.
Also, there is a lot of marketing and PR about some PowerApps integration with SharePoint 2019 I could not find much evidence of any changes since SharePoint 2013. I wish someone can comment on that to correct me. But by the same token we can also claim that SQL server 2008 has PowerApps & Flow integration.
You will have to setup an on-premises gateway in order to connect PowerApps and Flow to your on-premises SharePoint 2013/2016/2019. All development experience will be in the cloud, in non-sharepoint website(s). Users will have to consume PowerApps by going to an external website as well. You can always add PowerApps form to a SharePoint page as an iFrame. But it's an iFrame nontheless.
