Thank you Rob, I forgot to mention we are running Horizon Version 2312 at the moment.
I'll attach some screenshots, in the registry it shows the Smartcard Features as Absent for whatever reason.
The other two screenshots show the features I'm installing it doesnt event list Smartcard as an option there, when I install the Agent on a Windows 10 Desktop for example, I see the Smartcard Feature as an option. (Sorry screenshots are German)
I found this Link Horizon Agent Custom Setup Options (vmware.com) where it says the feature is only for Single User machines. Thats for Horizon 7 tho, so I'm not sure if that has changed in the meantime.