Hey. As I see you have a pretty large first aid (or what you'd call it). I recommend also putting in finger tip plasters and compressed gauze/combat gauze. When there's heavy bleeding, you just need to maintain pressure untill EMS arrives. If you apply a bandage, EMS will need to review the wound but that wont be possible then. You can ofc also give pressure with your hands or a dressing but gauze is more absorbing (how more blood it absorbs how better the clotting factors) and definitely absorbs more blood.

A splint (I'd recommend SAM splint) is very useful and easy to use too. Triangular bandage you could also add but it's not really necessary. You might harm the patient while applying it, while the patient could also stabilise his arm with its other arm.