I've started a new Geyser fund for Libre Relay: https://geyser.fund/project/librerelay
I've ported Libre Relay to Bitcoin Core's new v28.0rc1 release, and I'm trying out Geyser to see if I can get my time paid for. I'll release the code if I do.
https://petertodd.org/2024/one-shot-replace-by-fee-rate
One-Shot Replace-By-Fee-Rate
tl;dr: we can solve Rule #3 transaction pinning attacks by simply replacing based on fee-rate, if the old transaction wasn't going to be mined in the next block or two, and the new transaction will be.
This _is_ incentive compatible, because it makes more sense to make money now with a high fee rate transaction than to favor a transaction of lower fee rate that may never even be mined.