[outsidein]

Flip it twice. Once to determine which side is up at second throw. Reverse to counter bias at start of second throw. Then flip again for final result.

[two_handfuls]

That only works for a fixed bias, it's gameable if the person tossing the coin controls the bias.

[outsidein]

That is outside the preconditions of the paper: „if the person tossing the coin controls the bias“

[Aloisius]

This won't fix the bias. It would be biased towards the obverse of the starting side up of the first flip.