I'm not certain of it but i believe there is at least another difference between the Trekhy and the system Novacium is in the process of creating for HPQ.

I believe the Trekhy was not built to work under pressurized conditions.  

From yesterday's NR;

Targeting net-zero emissions by 2050, the focus is on the green, low-cost production of High Purity Silicon, fumed silica, and an autonomous pressurized hydrogen delivery system.

There is no indication about how much pressure the new system will be working under, nor about what benefits a pressurized system would bring, but I guess we will find out in the near future.