https://gist.github.com/ba257ce953c3d50cd7cd257c8f627279 but with randomized animals as well

flanimal.js

const
	flags = [
		Uint8Array.of(
			1,
			2,
			6,
			11,
			12,
			13,
			15,
			16,
			18,
			20,
			21,
			25
		),
		Uint8Array.of(
			1,
			6,
			11,
			18
		),
		Uint8Array.of(
			2,
			4,
			11,
			12,
			13,
			18,
			19,
			21
		),
		Uint8Array.of(
			0,
			1,
			2,
			6,
			8,
			12,
			18,
			19
		),
		Uint8Array.of(
			0,
			1,
			3,
			4,
			6,
			8,
			9,
			10,
			12,
			13,
			15,
			17,
			18,
			21,
			24
		),
		Uint8Array.of(
			0,
			1,
			2,
			6,
			12,
			13,
			15,
			19,
			22
		),
		Uint8Array.of(
			0,
			1,
			2,
			4,
			6,
			10,
			12,
			13,
			15,
			18,
			19,
			20,
			21
		),
		Uint8Array.of(
			0,
			1,
			2,
			4,
			6,
			10,
			12,
			15,
			18,
			19
		),
		Uint8Array.of(
			1,
			2,
			5,
			6,
			10,
			11,
			13,
			18,
			21
		),
		Uint8Array.of(
			1,
			3,
			5,
			18,
			19
		),
		Uint8Array.of(
			2,
			3,
			5,
			7,
			11,
			12,
			15,
			18,
			19
		),
		Uint8Array.of(
			0,
			1,
			2,
			6,
			8,
			12,
			13,
			15,
			18,
			19
		),
		Uint8Array.of(
			0,
			1,
			2,
			3,
			5,
			6,
			7,
			8,
			9,
			10,
			12,
			14,
			15,
			18,
			19,
			20,
			25
		),
		Uint8Array.of(
			1,
			2,
			6,
			7,
			8,
			10,
			12,
			15,
			18,
			19,
			21
		),
		Uint8Array.of(
			0,
			1,
			2,
			3,
			5,
			8,
			9,
			12,
			13,
			17,
			18,
			19
		),
		Uint8Array.of(
			6,
			9,
			10,
			12,
			13
		),
		Uint8Array.of(
			0,
			1,
			6,
			8,
			12
		),
		Uint8Array.of(
			0,
			1,
			2,
			4,
			5,
			6,
			7,
			8,
			10,
			11,
			12,
			13,
			15,
			18,
			19
		),
		Uint8Array.of(
			0,
			1,
			4,
			6,
			8,
			11,
			12,
			15,
			17,
			18,
			20,
			22
		),
		Uint8Array.of(
			0,
			1,
			4,
			6,
			7,
			8,
			11,
			12,
			15,
			18,
			19,
			24
		),
		Uint8Array.of(
			0,
			2,
			6,
			7,
			11,
			12,
			13,
			17,
			21
		),
		Uint8Array.of(
			1,
			2,
			11,
			12,
			18,
			19
		),
		Uint8Array.of(
			0,
			1,
			2,
			6,
			10,
			12,
			15,
			17,
			19,
			25
		),
		Uint8Array.of(
			0,
			2,
			12,
			18
		),
		Uint8Array.of(
			1,
			2,
			6,
			10,
			11,
			12,
			15,
			18,
			20
		)
	],

	a = 0x1f1e6,
	randIdx = Math.random() * flags.length | 0

String.fromCodePoint(a + flags[randIdx][Math.random() * flags[randIdx].length | 0], a + randIdx, 0x1f400 + ~~(Math.random() * 65))