There probably is an optimized first flag guess that covers the maximum possibilities of all flags, like how Seychelles has almost all the colours in diagonals so you can cover a lot of space

Flagle #990 - 4/6 🏁

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🟩🟩🟩🟩⬛
🟩🟩🟩🟩🟩

https://flagle-game.com/

Flagle #990 - 6/6 🏁

⬛⬛⬛⬛⬛
⬛⬛⬛⬛⬛
⬛⬛⬛⬛⬛
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🟩🟩🟩🟨⬛
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https://flagle-game.com/

That were some unlucky first guesses at the start…

Flagle #990 - 2/6 🏁

🟩🟩🟨⬛⬛
🟩🟩🟩🟩🟩

https://flagle-game.com/