First i must say i like vyos very much and am gratefull to developers.
Netflow in its current form is only thing preventing me from switching to vyos.
Now, the answer.
“Unusable” because there is no way to do it with configure commands, it reverts to original state after every system update and state is not reflected in config.boot.
“Almost” because workaround exists.
If you configure netflow export like on any other router you will not get what you expect.
There is no egress accounting and ingres capture defaults to pre-dnat which is little problematic on routers that do NAT.
Ubiquity fixed this with
set system flow-accounting ingress-capture [pre-dnat | post-dnat]
set system flow-accounting netflow enable-egress
and i hoped it would trickle down to vyos.