Shadowrun Boggles – Personafixes and Bioware

I’m building a decker character whose uses a personafixes to be a better…person in general. Essentially he is a blank slate (from prolonged personafix use) and uses a custom personafix to just be a functional professional. As I was asking advice on what a decker character should have it was recommended bioware that boost initiative like cerebellum boosters. But that got me thinking how much of a brain does the personafix override or bypass. Like I can’t imagine that a normal person’s brain would remain intact if the personafix overwrote the neurons in the brain. I thought it bypassed the brain (with data filter cyberware? RAS override?) and used the BTL jack to allow the persona to use the body and act out it’s programming. But if that is true then a personafix personality might not be able to make use of any augmentations that restructure the neurons. That leaves augmentations that improve nerve connectivity sure, but am I right in this thinking?

EDIT: I am probably overthinking it, hence my question of how the personafix interacts with the brain.

So for example, a mneumonic enhancer is said to add a chunk of gray matter to the brain’s memory centers to improve knowledge tests, but if all the character’s knowledge and memories comes from the personafix chip this would be useless.

But the synaptic booster broadens the nerve paths in the spine so messages between the personafix chipjack and the body would indeed be faster.

Given those two examples how useful or useless should other cyberware and bioware be to what is essentially a chipjack running a person’s body.

TLDR: character is essentially a bunraku puppet with the personafix of a competent decker, a chipjack driving a person. So obviously overthinking, but which augmentations should or should not be useful to that chipjack.