More datamined code on gravity alteration, thermodynamic simulation, etc.
References to Nvidia CUDA Cores which he speculates to either be for raytracing or physics calculations
Most importantly, Valve have expanded from internal dev-team playtests into Family&Friends Playtesting
For context, these are the bigger playtests that caused Deadlock to completely dumpster its old Neon Prime setting back in late 2023. It also what caused Erik Wolpaw and Jay Pinkerton to come back to Valve to rewrite Half Life Alyx back in 2018/2019 after the previous iteration of the story left playtesters wanting a bit more. Furthermore, both of those writers are still at Valve and they're not writing for Deadlock so besides the recently finished TF2 Comic they must be doing something else at the company.
If this larger playtesting phase goes smoothly apparently it's possible that HLX could be announced as early as 2025.