Yes

Horde Breaker says:

Once on each of your turns when you make a weapon attack, you can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of your weapon.

and Commander's Strike says:

When you take the Attack action on your turn, you can forgo one of your attacks and use a bonus action ...

You take the Attack action meeting the first criteria of Commander's Strike. You make the attack while another creature is within reach of your weapon and 5 feet of the target meeting the criteria for Horde Breaker. You gain an additional attack which is not a bonus action so must still be under the umbrella of the Attack action (not that this is a requirement). You forgo that attack meeting the second criteria of Commander's Strike and use your bonus action meeting the third.

Well spotted.

Yes, you can forgo the additional attack from Horde Breaker and use Commander's Strike.

Horde Breaker says:

Once on each of your turns when you make a weapon attack, you can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of your weapon.

and Commander's Strike says:

When you take the Attack action on your turn, you can forgo one of your attacks and use a bonus action ...

You take the Attack action meeting the first criteria of Commander's Strike. You make the attack while another creature is within reach of your weapon and 5 feet of the target meeting the criteria for Horde Breaker. You gain an additional attack which is not a bonus action so must still be under the umbrella of the Attack action (not that this is a requirement). You forgo that attack meeting the second criteria of Commander's Strike and use your bonus action meeting the third.

Well spotted.

Yes

Horde Breaker says:

Once on each of your turns when you make a weapon attack, you can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of your weapon.

and Commander's Strike says:

When you take the Attack action on your turn, you can forgo one of your attacks and use a bonus action ...

You take the Attack action meeting the first criteria of Commander's Strike. You make the attack while another creature is within reach of your weapon and 5 feet of the target meeting the criteria for Horde Breaker. You gain an extra attack which is not a bonus action so must still be under the umbrella of the Attack action (not that this is a requirement). You forgo that attack meeting the second criteria of Commander's Strike and use your bonus action meeting the third.

Well spotted.

Yes

Horde Breaker says:

Once on each of your turns when you make a weapon attack, you can make another attack with the same weapon against a different creature that is within 5 feet of the original target and within range of your weapon.

and Commander's Strike says:

When you take the Attack action on your turn, you can forgo one of your attacks and use a bonus action ...

You take the Attack action meeting the first criteria of Commander's Strike. You make the attack while another creature is within reach of your weapon and 5 feet of the target meeting the criteria for Horde Breaker. You gain an additional attack which is not a bonus action so must still be under the umbrella of the Attack action (not that this is a requirement). You forgo that attack meeting the second criteria of Commander's Strike and use your bonus action meeting the third.

Well spotted.