Depends how far you want to take it but consider
CPR face shields
Sandwich bags with handles (put valuables in and attach to person.)
Toe tags (laminated card with string through it to write up what you’ve done so can give a HOTO to paramedics)
Headtorch & cyalumes.
Maybe consider some Sam splints and cling film to put on burns to keep clean.
Plus I assume in your car you have 2x hi-vis vests, a fire extinguisher and a decent warning triangle.
all absolute overkill until you need it. which you might on a country road with little phone signal. Have had someone keel over behind me and having to give mouth to mouth, I was glad I had a face shield in my wallet. A mate had to look after someone for 20 minutes as he and his doctor wife were first on the scene. He said it was annoying how little they could do to help despite their knowledge as they had no kit.
obviously doing too much when not qualified is not a good idea.
One of my former colleagues, a trauma surgeon by trade, had been on the Tube train that got bombed - and was called to give evidence at the enquiry.
All he had with him was a biro, he said. When sh1t happens, it comes at you like a piano falling off a building.
All the training and experience you have boils down to doing the best you can, with what you have to hand.
That said, bravo for putting a decent kit together.....I will roust out my own similar green pouch and check off how lacklustre it is....still have a couple of Catsticks and a shrink-wrapped wound dressing somewhere .
( I have toyed with enrolling with St John's ever since I worked with a maniacal St.J lifer in Victory Building back in the previous Century )