I am already using a system that takes customer info and generates a password for them, which is then emailed to them. If they never return it works the same as PWA since they don't have to choose a password or provide any information other than that required to fulfill the order. But they do have an account and can change the password if they wish to return later and want a less random one. And I can see their orders and information.
I had found an add-on, which I have heavily modified and updated to work with 2.3.4. I don't remember the name for sure. It was "combined login/create account" or something similar. I thought about putting together an add-on of my own since the original had a lot of problems, but I haven't found the time.