SharePoint Server Subscription Theming / Font

I have two questions about theming/branding SharePoint Server Subscription (not Online)

1. Apply theme

To use a new specific company color schema I want to use a custom Theming for modern pages:

https://learn.microsoft.com/en-us/sharepoint/dev/declarative-customization/site-theming/sharepoint-site-theming-overview

To apply the new theme I found the PowerShell commands for SharePoint Online:

https://learn.microsoft.com/en-us/sharepoint/dev/declarative-customization/site-theming/sharepoint-site-theming-powershell 

But how can I apply the custom theme in SharePoint Server (Subscription)? Regarding the SharePoint Server PowerShell cmdls there is no "apply-theme" command: https://learn.microsoft.com/en-us/powershell/sharepoint/sharepoint-server/sharepoint-server-sub-cmdlets

2. Font family

It is possible to apply a company specific font in the modern experience mode? All classic layout options (MasterPages, composed looks etc.) not useable. The only option that I found so far needs an SPFx application customizer.