Would it even be in the realm of possibility to upload the Ti-Nspire OS to a Ti-84 Plus CE calculator? If so, what conditions would need to be met to achieve this? I like the layout of the OS and feel that my Ti-84 calculator is getting boring, so I hope to do this and make my money's worth. Thanks!

I'm not an expert in this field, but I'm pretty certain this isn't possible. Mainly due to different CPUs (Nspire has an ARM926EJ-S processor (thanks for that info grosged!), and the CE has a very different eZ80 processor) and other hardware differences. Even if it were possible, the processor of the CE is slower than the Nspire, rendering the OS obsolete.

If you really want an Nspire-like OS on your calcualtor, you could try making a shell in C or ASM to emulate it.

Experienced people, if any of my information is incorrect, please correct me!

It would not be possible to do that. The Nspire is a completely different device than a TI-84 plus CE; it is much more powerful. Even if the OS was compatible, just the OS itself is 15Mb, which is about 7 times the total amount a CE has.

Thanks for answering. I guess I never really thought about the speed difference, as well as storage problems. I guess I'll make an emulator (well, at least attempt to...)

Unless you're BrandonW, it's impossible.

I think that Mateo could probably make an emulator of the TI-Nspire for the CE.

TL;DR: forget about emulating the Nspire series on any other calculator model, from any manufacturer, currently on the market. That is, without hardware extensions.

TI-Z80, TI-eZ80 and TI-68k calculators have, at best (namely, for the 83PCE/84+CE, the V200 and the 89T), 1/8 of the amount of Flash of the oldest, discontinued '2007 Nspire Clickpad calculators (4 MB vs. 32 MB), and more importantly, a tiny fraction of the amount of RAM of the same Clickpad calculators: 256 KB vs. 32 MB.
The '2011 Nspire CX calculators have 64 MB of RAM and 128 MB of Flash; six years and a half later, this amount of RAM, which is ridiculously small for non-ruggedized hardware sold at such high price tags, remains the highest available on a calculator. At best, they could emulate the Nspire Clickpad & Touchpad, but that's not very useful.

With external hardware, everything is possible... but that's not to say it will be practical
I remember about someone who made an ARM emulator for his 8-bit AVR, and used it to boot Linux + trivial user-space. It only took several hours to reach the shell prompt.

Let's go back to the original post:

The oldest releases of the Nspire OS for the Clickpad & Clickpad CAS are smaller than 4 MB, so yes, strictly speaking, it would theoretically be possible to upload the TI-Nspire OS to a 84+CE calculator. Not that you could do much with it, per the above

As for a sketch of the conditions:
* on the TI-68k series, besides modding PedroM to include the 2639367 bytes of binary data from the Nspire Clickpad CAS OS 1.1.9253 .tnc file, which would definitely work, maybe an XPand-patched AMS 2.07 running on a V200 would let one store this much data + the FlashApp metadata as a single piece. The latest OS 3.10 running on a 89T wouldn't.
* on the TI-eZ80 series, besides a nonexistent non-toy full-custom third-party OS as well... jumping through hoops to create a custom FlashApp while it's being transferred, I suppose.