Not the same, actually! Unlike the TI-83/84 series, the TI-89, -92, and Voyage-200 all used a 68000 CPU, with a completely different (and much better) operating system.
I wrote a web-based emulator for the Voyage-200 a few years ago: https://woofle.net/v200/
[1] Except the screens on the older models were truly horrible, from a brightness and contrast perspective.
[2] From my recollection, the calculators interfaced with hardware and software from other vendors. Then, of course, there was the vendor lock-in provided by textbook publishers.
I agree that you not need to have more powerful calculator. A cheap Casio or HP calculator it's enough for the 99% of time. I keep using my old Casio from my formative years. It's in an interesting calc. Powerful enough to write formulas and complex calculations, but can't store formulas or programs. Just in the nice spot that allowed it to be used in exams.