optimal_bvmap の std/style.json で使われている色のリストを作るには、次のようにすればよかった。

curl -s https://gsi-cyberjapan.github.io/optimal_bvmap/style/std.json | jq '[.. | select(type == "string" and (. | test("^rgba\\("))) | .] | unique'
[
  "rgba(0,0,0,0)",
  "rgba(0,0,0,1)",
  "rgba(0,0,255,1)",
  "rgba(0,155,191,1)",
  "rgba(100,0,0,1)",
  "rgba(100,100,100,0.5)",
  "rgba(100,100,100,1)",
  "rgba(100,195,115,0.5)",
  "rgba(100,195,115,1)",
  "rgba(150,150,150,1)",
  "rgba(173,173,173,1)",
  "rgba(175,74,24,1)",
  "rgba(19,97,69,1)",
  "rgba(190,210,255,1)",
  "rgba(20,90,255,1)",
  "rgba(200, 160, 60,1)",
  "rgba(200,160,60,1)",
  "rgba(200,200,200,1)",
  "rgba(200,250,230,1)",
  "rgba(217,217,217,1)",
  "rgba(231,39,65,1)",
  "rgba(235,130,120,0.5)",
  "rgba(235,130,120,1)",
  "rgba(235,242,235,1)",
  "rgba(255,119,51,1)",
  "rgba(255,135,75,1)",
  "rgba(255,187,153,1)",
  "rgba(255,230,190,1)",
  "rgba(255,255,0,0.5)",
  "rgba(255,255,0,1)",
  "rgba(255,255,255,1)",
  "rgba(34,24,21,1)",
  "rgba(50,50,50,1)",
  "rgba(60,50,181,1)",
  "rgba(68,0,128,1)",
  "rgba(80,80,80,1)",
  "rgba(81,29,10,1)",
  "rgba(96,25,134,1)"
]