I have also done similar research because I wanted to build something to handle microtransactions on a personal website that could scale if adopted to be usable by everyone if they wanted.

I looked at crypto currency because it seems like the obvious naive solution. it doesnt work. the cost of the transaction itself far outweighs the value of the transaction when dealing with fractions of a cent. you want an entire network to be updating ledgers with ~millions of records per ~$1000 moved. the fundamental tech of crypto leans towards slower, higher value transactions than high volume, small transactions. Lots of efforts have been made with some coins to bring down the bar of "high value, low volume" to meet everyday consumer usage rates and values - but a transaction history at the scale of every ad impression for every person is a tough ask and would perpetually be in an uphill battle against energy costs.

Ultimately, the conclusion I came to is that the service would need to be centralized, and likely treated as cash by not keeping track of history. Centralized company creates "web credits", user spends $5 for 10,000 credits, these credits are consumed when they visit websites. Websites collect a few credits from each user, and cash out with the centralized company. The issue is that since it would cost more to track and store all the transactions than the value of the transactions themselves, you have to fully trust the company to properly manage the balances.

I started building it and since I would be handling, exchanging, and storing real currency - it seemed subject to a lot of regulations. It is like a combination bank and casino.

i've thought about finishing the project and using disclaimers that buying credits legally owes the user nothing, and collecting credits legally owes the websites nothing, and operating on a trust system - but any smart person would see the potential for a rug pull on that and i figured there would not be much interest.

The alternative route of adhering to all the banking regulations to get the proper insurances needed to make the commitments necessary to users and websites to guarantee exchange between credits and $ seemed like too much for 1 person to take on as a side project for free