I stumbled across Prolific (https://app.prolific.co/) a year ago and in that time have earned about 367.93 pounds. It is a British site and so I've always got more money than I think once I do the conversion. The site does surveys for scientific and education studies. Much of it is people putting together their work for a Masters or Doctorate but some of it is legitimate sociology in action. The surveys span from the poorly constructed to the complex and relevant, from 'Why do men urinate standing up and how can I make them stop?' (yes, this was couched in what was going to be some kind of thesis) to investments, hiring practices, political thought, video games. An amazing array of topics people use for their final papers.
Most of the payouts are less than a pound. Some are more and sometimes it is a couple or three pounds. But the money typically grows very slowly. Right now I've got about 82 pounds in the bank that I can transfer anytime I want to PayPal and spend.
So I have long periods of time to decide what to spend it on and I do use a lot of brain cells on that. I've bought shoes, an Echo Auto and an Echo Show so far. It is zero guilt spending so it is kind of fun. But a lot of work.
I'm thinking about buying a battery powered mower next so I've got a ways to go before I pull the trigger. The longer I go, the nicer the mower. Right now I'm somewhere between https://smile.amazon.com/dp/B00HH4K548/?coliid=I328AXOIQ12F6D&colid=2GA7RLD7074SC&psc=1&ref_=lv_ov_lig_dp_it
Still thinking about it but spring approaches.