vyos@vyos# set policy route-map FOO rule 10 match ip nexthop 
Possible completions:
   access-list  IP access-list to match
   prefix-list  IP prefix-list to match

[edit]

vyos(config-route-map)# match ip next-hop 
  ACCESSLIST4_NAME  IP Access-list name
  address           IP address
  prefix-len        Match prefixlen of given nexthop
  prefix-list       Match entries of prefix-lists
  type              Match entries by type