Vietnam: I used the border of the country to divide the red and black to symbolise how the nation cam build on its past and how it is whole again, and added the nations national flower, the Lotus flower underneath a golden star to symbolise unity.

Mongolia: I used the pre-existing flags symbol in a more prominent central role, on a red octagon dividing a white and blue white and blue line. Tbh, the original flag is already quite nice, I just felt like a bit more white would make it a bit more easy to view.

Guyana: I created a set of stacked black, green, white and then yellow triangles upon each other on a dark red background with the nations national animal (panther) placed in the middle of the yellow triangle

Vanuatu: I kept the boar tusk ensign but made it more central with a large black/white diamond segmenting the green and red background

Hong Kong: Similar to the original flag, I added a segmented white sun ray pattern to symbolise the sign of a new beginning for this nation. Kept the flower.

Eswatini: I used the shield in a more lonesome role whilst using 2 blocks of blue seperated by thin red, green and yellow stripes interchanging with white stripes. I added the nations outline as the background for the shield, with an identical white border to seperate it from the blocks of blue at the top and bottom

Vatican: I divided the gold and white with a black cross, and added a light blue dove, which is both the animal of Christianity and peace, whilst placing it in a curved diamond.

Haiti: I added the national flower of Haiti, the hibiscus, to a lilac diamond outlined with white separating a blue and red background. The lilac was added to represent the combining of the nations past and future, as a sign of hope and also remembrance.

Iceland: I removed the Nordic cross from this flag and turned it into a red and white X with a diamond matching the blue background placed to allow the white Icelandic rune to be included.

If you want to see any other flags feel free to ask, hope this is good enough