The others have provided the link - I'll add it's the activation/licenses are the part you really pay to get but you can do that after install (or not at all, it's just nagware outside of some personalization settings).

Windows Server 2019 is going to have some wonky defaults and components out of the box. Some apps will report not being compatible but it's not usually a problem. That said, Windows Server 2019 is neither the oldest or newest version of Windows Server based on the Windows 10 codebase so I'm not sure why you'd bother with it in particular.

You'd be surprised to know the actual answer: Microsoft

https://www.microsoft.com/en-us/software-download/windows10I...

Fine print: You need a non-windows user agent, otherwise you get redirected to a windows-specific page with no ISOs.

As an aside, you might want to install Ventoy to your flashdrive:

https://www.ventoy.net/en/index.html

That way you just need to copy the ISO to the flashdrive.

You can get ISOs from the following link for Home and Pro edition but you have to visit the site from a non-Windows device (a different user-agent might also work)

https://www.microsoft.com/en-us/software-download/windows10I...

You can also download the iso using powershell

https://github.com/pbatard/Fido

This might be a joke I'm missing about the Windows 10 installation, but this page allows download of the Windows 10 Media Creation Tool: https://www.microsoft.com/en-us/software-download/windows10

I think visiting it on Linux (I assume anything non-Windows) shows a download link for the ISO instead.