Footer option missing in SharePoint on-prem Modern site

[KD1502]

Hello all , 

I am seeing footer option is not available in Microsoft Modern SharePoint site on SP2019 OnPrem.  I have already seen it is directly available in office 365 modern site. Is there any way to bring it in SP2019 Onprem site too? 

Or if there is no way  to enable this then how we can create it using SPFX extension ? Is it a good idea ?

[#2]

Unfortunately at this moment there are not plans to bring missing features that are in SPO to SP 2019