In my eyes (uneducated, consumer-level perspective) X86 is a huge question-mark for HMD devices like this, since the heat and power usage are so counter-intuitive for small form factors -- and mitigating those concerns usually actively works against the "higher-performance" nature of the chips. (low-tdp allowances, throttling, etc.)
Like I mentioned above, I really do wish y'all the best of luck with it. I just don't envy having to be reliant on an old and power-hungry architecture just because the newer, better architectures don't lend themselves to this sort of project yet. I hope the Simula One sticks the balance!
I'm sure one could do a more rigorous comparison, but IMO with the recent Intel/AMD chips you get pretty good performance/power.
Apart from that, x86 is IMO just easier to adopt. I wouldn't buy an ARM laptop right now (except for possibly a Macbook).
In a different tangent, I think the only way to get good ARM performance in a mobile format is to have custom-tailored silicon, like the Apple chips. Commercially available chips just don't compete with a i7-1265U or the Raptor Lake equiv.