Can we perform an in-place OS upgrade (From Windows Server 2016 to Windows Server 2019) on a server that hosts SharePoint 2019? This is a DEV server, so it is a single server setup.
Windows Server 2016 can be upgraded in-place to Windows Server 2019, but it is highly discouraged to do an in-place upgrade for OS with SharePoint installed.
The recommended way is to deploy the farm on Windows Server 2019, and then retire the older SharePoint servers by migration.
In conclusion, it is technically workable, but not recommended.