There are more options available for Bitcoin privacy, some of them are available today and others are work in progress.
Maybe you could include them in your report and investigate them more and try to learn from their examples to improve whirlwind in future.
Bitcoin sidechains could be used in future but I think we need to see upgrade on Bitcoin for that to be fully possible, just wondering, if we can have stupid ordinals why can't we have this as well? 

Everyone knows about Lightning Network that can partially function for improving Bitcoin privacy, but if you didn't hear until now, there is wallet called Mercury that is using Layer 2 with statechains:
https://mercurywallet.com/