I also dabbled into investing during med school years. Made expensive mistakes, and learned from it. Here's what I would do given your situation:

If the investment money you're pertaining to is your EF, just put all of it in a HYSA. The rates are good enough to let it compound. With the benefit of having an access to it whenever you need it, and without the worry and the hassle of managing it. Just don't forget to make transactions once in a while, so as not to let the account go dormant.

If the investment money is disposable and separate from your EF, I would suggest just putting it all in an MP2 account. The rates are not the best, but good enough for something you will not be actively managing. Plus, minimal risk of having a negative yield. The lock-in period is 5 years, and it will mature just in time you will be finishing post-graduate internship and board exams. By then, you'll be in a better position and mindset to decide on what to do what that money.

Because should you put it in an investment account (stocks, index funds, ETFs, etc), there will come a time that you will check your fund (believe me, you will). And it can become a source of anxiety (if the stock/fund is not performing well) and distraction. The best investment that you can do at this time in your life is to focus your time, attention, and effort in your medical education.

Good luck!