PoP RAM can be touched. I have seen companies who have machines and ability to do so. But, what will system and SoC do about it? One is HW side, second is compatibility and so on.

N900 has 32GB + up to 64GB (or 32 only?) MicroSD card. N9 & N950 have no SD slot.

I understand what he wants to do and why. I just... use 1GB swap, it will work, even if slow. but that is not for daily usage anyway.