@artooro Did you try listen-port option for this case?
set service https api gql set service https api keys id KID key 'foo' set service https api socket set service https virtual-host foo listen-port '2580'
Check:
vyos@r14# sudo netstat -tulpn | grep nginx tcp 0 0 0.0.0.0:2580 0.0.0.0:* LISTEN 3570/nginx: master tcp6 0 0 :::2580 :::* LISTEN 3570/nginx: master [edit] vyos@r14#