Neither of those solutions solve the problem. The problem is two players at the same table sharing information about their hands.
Anonymizing identities doesn't matter if me and my accomplice know each other in real life and can just pick the same table.
IP addresses are totally useless for anything related to identity verification.
The only thing I can think of is a trust ranking or public statistics on your play. Stats like how often a player sat at the same table as another player and how often they played a hand together and other stats that may be relevant to collusion only. Along with stats, you can have an approval system to sit at the table. If 80% of a persons hands were played at the same table as another player, the other players at the table can disallow that player to sit.
I don't know. Just throwing out ideas.
The thing about blockchains is that every time you play you can be a new user.
How about making your seat and table random? The player can't choose where they play.
Pokerstars has 'Zoom' tables at multiple stakes.
There are usually a couple of hundred people in the zoom pool at any one time.
After each hand you are zoomed to another random table & given a new hand, this is to speed up the action but it also means you can't collude because the likelihood of you sitting at the same table as your colluders enough is very low.
Also I'm sure 80% of the poker volume is under 2/4 ($400 buy-in tables) and at those levels colluding is pretty pointless. Winners at those stakes are either bum-hunting (seeking out & getting position on weak/recreational players, no collusion needed, not worth it.) or they're mass multi-tabling playing 8-24 tables at the same time, making so many decisions so quickly it's not possible to collude. (They break even and live off rake-back*)
Rake* you showed the rake table earlier in the thread which looks lucrative for shareholders but bear in mind players can get anywhere from 20-60% of that back on most sites via rake-back. So you'd probably have to undercut that model by 75% to be attractive.
A bigger problem at lower stakes than colluding is bots, many people have automated bots that just play basic strategy on multiple tables and eek out a profit.