I have been studying quite a lot about Account abstraction and ERC-4337 recently. I will point out here some resources worth reviewing:

• Walk through a thinking process of arriving at the current AA design, showing which problems had to be resolved along the way: https://www.alchemy.com/blog/account-abstraction

• Modularization of AA: https://blog.rhinestone.wtf/modulekit-deep-dive-ad84ee0797c6

• Early experimentation with AA by Visa: https://usa.visa.com/solutions/crypto/auto-payments-for-self-custodial-wallets.html

• Panther Protocol explanation of AA: https://blog.pantherprotocol.io/ethereum-account-abstraction-everything-you-need-to-know/

• SDK facilitating operations on AA: https://accountkit.alchemy.com

• Safe Wallet implementation for AA: https://safe.global/core