How do I find the right paint to cover up this hole in the wall?

You won’t need a whole gallon. Take a paint chip to the store and have them color match it. Most stores now have no problems matching paint. Then buy the smallest size can of paint they have, it will probably be a pint or a quart.

Thank you for your help, @WestRiverrat ! How do I get the paint chip? Just lightly take a piece from the wall?

Try using the putty knife to scrape off a piece of paint about an inch in diameter, and take it to a paint store for matching. At most places, you can even buy just a small sample of the paint these days, so no big investment.

Thank you, @augustlan :-)

In my practice it would be a miracle to achieve an exact match. Even if you still have the exact can of paint that was used to do the job before, it probably won’t match if it has been a while. The paint on the wall has faded some, gotten dirty or some such and it will show. You can feather away from center to eliminate a hard line to blend it better, and Paint will have a different sheen when it goes over filler as apposed to a painted surface so at least two applications over the filler will need to do a proper build up. Also to add to the uncertainty is different lot #‘s of the same base color will be slightly different if getting new paint is the chosen remedy. I have discovered that it’s best to have a manual batch made by the gallon instead of quarts.The mixing formulas seem to be more accurately calibrated for gallon sizes and besides, a gallon of paint isn’t a whole lot more in cost that a qt. With quarts it becomes a crap shoot. Unless the entire wall is painted, cut in from corner to corner, baseboard to ceiling, there may be a tell tail sign that there was a repair. But that may involve moving too much stuff and involve more than you feel like doing so then it can become a matter of what you are willing to accept as good enough. That is the spiel my customers get and leave it up to them to decide what they want. I’m good but I’m not a magician. If they want perfect then they will understand on the front end it’s gonna cost. If they want to just fix it “good enough” they can keep it real and do it the cheaper way, but at least they’ll understand what’s going on and there will be no surprises.