I'm not sure if your question has been answered fully so I will try and do my best:
The quick answer is no, and even the more detailed answer is no, given the specific wording of your question.
Let's try it this way around:
(1) Foveated rendering means more detail where your eyes can see it and in turn less detail where they can't. Given that current HMDs have a fixed clear area in their optical design, we already have engines that render most detail within that 'sweetspot' and less detail outside of it, at virtually no cost to the user's experience but providing the ability to really crank it up 'where it matters'. So in theory (HMD specific variables such as size of sweetspot would have to be customized on a per-HMD basis) the Pimax 8K is ready for this type of foveated rendering.
(2) Eye-tracked foveated rendering doesn't assume the size of a sweetspot to decide 'where it matters' as its basic metric, but in fact 'where your eyes are looking at'. This allows for specific experience mechanics such as eye-tracked gaze control.
(3) It also allows for what has been mentioned in this thread, that is an eye-tracked adjustment of the geometric distortion algorithm so that the optical sweetspot of a panel/lense configuration can be 'moved' in sync with your eye-movement. Given that Pimax appear to strruggle with even the somewhat less complex sweetspot and IPD variable geometric distortion algorithm, I do not believe that a player of their size as capable of the required R&D until it becomes a verry possible industry standard.
What is also possible is to combine (1) and (2) [and theoretically even (3)] so that the engine renders a circular area at the focus of both eyes at the highest detail and then gradually decreases detail going from center to periphery. This is what Tobii as well as some others have shown. Problem is, there is no standard for sample rate and positional prediction yet, so engine developers are reclutant to invest considerable ressources into this feature until at least a roadmap for hw and river developement is agreed on. Yet in theory, given that Pimax decide upon an eye-tracking solution that satisifies the stated requirements, the 8K will be ready for that. All it needs is an interface for the tracking solution.
What you are asking though, if I understand it correctly, is if given current specifcations of DisplayPort, HDMI, USB-C, thunderbolt etc is if it will be possible to have the 8K not only display more DETAIL within the eye-tracked foveated panel area, but in fact display at at the panel's NATIVE 4K resolution. This is absolutely NOT possible and would have to be a feature added to an IO specification such as e.g. DisplayPort and agreed upon by the industry.
So no, the Pimax 8K will not be able to ever display any area of its panels at any RESOLUTION higher than it's native input res which is limited to 1440p. It will in all likelihood, however, be physically able to display more DETAIL in any given panel area, based on either eye-tracked or simply fixed foveated rendering.