Clothes.
A first aid kit
Very important that whatever first aid kit you get has a tourniquet, or that you buy one separately.
They are easily the most important life saving device in any first aid kit. 99% of the time you wonโt need it for normal cuts but when you are dealing an injury that needs one you WILL regret not having one.
A toothbrush
Using it but not owning it sounds kinda gross in the context of toothbrushes tbh.
If you are going to splurge, an electric toothbrush brush just feels better - although manual are just as effective when used properly.
A door lock