Actually the panel (and PCB) dimensions simply are based on Intellijel ones, and the major (or minor?) change is about the mounting holes that are open on the outsides. That's it. So there will be tiny gaps when used within PL cases, yet you can use screws on top AND bottom.
Recently, a couple of manufacturers apparently adopted this method : Synthrotek, Winterbloom, and EcoLab (for the latter, their 1U modules are not on Modulargrid yet, and these have been showcased on Instagram over the past few days).