I think everything I need know is sfx for coins and maybe jump and maybe for wood UI for my game https://dustdfg.itch.io/greedyslime So I will just give you an advice because I think I will find what I need if I will try to do it....
If you want to create portfolio, I would advise you to create sfx pack (coins, jump, death, hurt...) with a CC license maybe CC0 or CC-BY or CC-BY-SA... It's enough popular things and it isn't so difficult to make it so it will help you to start...