For "l2vpn evpn" it's necessary that the interface "vxlan" supports some additional commands.
Including commit without specifying a remote address.
In l2vpn evpn you don't need a multicast or a static indication of a neighbor.
To deploy BGP EVPN, a typical solution is to use several route reflectors (ref below).

An example, we can't execute analog of this command in the VyOS syntax:
sudo

ip link add vxlan11 type vxlan id 11 dstport 8472 local 22.22.22.1 nolearning

VyOS

sever@vyos-1.3-roll# compare 
[edit interfaces]
+vxlan vxlan11 {
+    port 8472
+    vni 11
+}
sever@vyos-1.3-roll# commit
[ interfaces vxlan vxlan11 ]
WARNING: RFC7348 recommends VXLAN tunnels preserve a 1500 byte MTU
Group or remote must be configured
[[interfaces vxlan vxlan11]] failed
Commit failed
[edit]

Ref https://vincent.bernat.ch/en/blog/2017-vxlan-bgp-evpn

Also, we need to add commands for vxlan:

• local
• nolearning