1) I can vouch for usertesting.com. Each test can pay out $10 and you'd be doing 10-20 minutes of work on average just rating website interfaces. There are interview-type of tests that can pay $30-60 for a half-hour or hour session i think but those are hard to qualify for. Payout is via Paypal for me. I've been doing tests since I was in high school just here and there. Some tests require a webcam to show your face and some you can do on your phone. There is a screening for tests so you'd have to take a survey.
2) You can also do affiliate marketing with Amazon. Basically if you're good at blogging or making videos, you link the products using a unique link and people click on it. If they buy that product, you earn commission. It can only really work if you have a big online presence or some sort of influence.
3) I've done stock photos in the past. I took some pictures and uploaded them to sites like Adobe Stock and ShutterStock and you can get some commission. It's not guaranteed though. And the pictures have to be very high quality and have to meet certain standards.
The above listed are supplementary income.