I don't believe I've ever seen them in regular over-the-counter emergency kits, but making sure you have a tourniquet within (and know it's use) reach can't hurt. A pocket mask is great, too. An AED would probably be amazing if you have over a thousand US (or it's equivalent) dollars to spend. Emergency treatments in general change pretty drastically every few years, so it would be an ongoing investment.

Have a good, working knowledge of what diabetes looks like, and various cardiac issues. While it may never happen to you, recognizing it and calling for help might save someone.

The training, naturally, is probably the hardest part to acquire, but I don't think anyone who maximizes learning efficiency would have any trouble. The main issue is finding the right teachers.

While I could come up with a curriculum (I teach very basic survival/emergency treatment regularly) and put it in a nice app or something, the nature of those treatments are constantly changing, and I wouldn't in good conscience disseminate that information without knowing that students would be able to stay up to date.

Until then, an EMT course can't hurt. If you have stable employment and decent hours, you might be able to take advantage of night classes.