From my xp and learning about pimax’s structure. The Crystal in part was already being explored. That being said pimax since there very first p1:series(yes plural) have used a shared shell/casing. Designing and making new molds is very expensive.
The 8kX itself was the intended 8k model pimax wanted to release; however it was discovered that at a time prior to launching the KS that a combination of factors regarding tech available that native 4k/eye was not doable. This resulted in the compromised upscaled 8k. Due to community pressure pimax committed to make a limited number(400 units) of prototype 8kX with a ? on when it might release. The 5k itself was a suggestion by the community member @Davobkk whom was apart of a focus group Xunshu organized within the original pimax forum.
Pancake lenses as pimax explained do have issues with light transmission if I have the term correctly. @mmorselli created a topic to get more clarity on the stated 15% on this statement.
I found an article that verified pimax’s statement and actually explained the “15%” statement was generous and maybe lower efficiency. It is a great read as it gives a detailed explanation of pancake lenses design. To which I thanked Mmorselli as I would not have read that very “illuminating” article.
Read his topic here
With the ET from Tobii with the 12k they are collectively working out how to mount the sensors as the lense design is much more complicated. Iirc I read that somewhere in r/pimax; disclosure this was not a statement by a pimax employee but someone that may have close contact with a team member.