The point of all of that hashing is to guarantee that transactions can’t be reversed (finality). A blockchain is a directed graph, for it to be a single irrever

The point of all of that hashing is to guarantee that transactions can’t be reversed (finality). A blockchain is a directed graph, for it to be a single irreversible source of truth, some mechanism has to force it to have a linear topology. Your ideas are interesting, but I can’t see how any of your examples could be used to achieve that topology. Also, the “POUW” examples you have are incredibly slow, developing codecs is going to take at least days, more likely weeks, months, or even years, meanwhile users will have transactions that need to be settled. You mentioned CO2 in your statement about disliking cryptocurrencies but there are many currencies that do not utilize proof-of-work, instead using other schemes (e.g. proof-of-stake), I’m curious if you dislike those as well.