Hal would have used Monero
Reading Hal Finney's "Protecting Privacy with Electronic Cash" after a discussion with nostr:npub1w69ya7xs697hk3hky3gllryz8rwverfa0ylz89chf9qnhfcskc2s64zltw and nostr:npub1j4u5gjzjyggr3h96x3gjy4akdgwxuk7mgvumv72gym2qyje7fn5s47d6x9.
I think Hal would have liked the combination of bitcoin + Nostr + eCash as a creative way to describe the problems he talks about here.
https://nakamotoinstitute.org/library/protecting-privacy-with-electronic-cash/
Discussion
He said in some newspaper that electronic cash needs to have untracable transactions to replace real cash.