I hope this isn't an obvious question. What I can find after digging around is:

the Usamune Practice Rom will not work with your Everdrive/ED64 and on Gameshark you are limited to only 13 lines of code, which means you will be unable to use most practice codes.

dagoth | everdrive

Is that it? The Expansion Pack has no direct impact on Super Mario 64? I thought maybe, possibly, it would have faster read/write than the bundled RAM.

Recommended changes

• I think the explanation of why to buy an OEM Expansion Pack should be in alaris' linked N64 Buyer's Guide in Resources.

N64 Setup Guide for SM64 - Google Docs under alaris' link in Resources:

• The guide must be years old because it's recommending buying a Sony PVM/BVM. A 20" mono PVM that does RGB runs well over $1000 USD today and a BVM is looking like $2000 + has no audio inputs. Let's not recommend pro monitors anymore! Sad seeing people show off their 9" pro Sony monitors on Reddit that have lower TVL than consumer 15" sets that get dumped on the curb. Further, JVC, Ikegami and others made nice pro CRT monitors that go for less.
• The guide has an AmaRecTV setup versus OBS and gives AmaRecTV more weight. Years ago I could understand but I think I can say without controversy that there is no reason to use AmarecTV over OBS today, unless you have a very specific reason. Like you want to capture off of Windows XP. The guide even links's EvilAsh25's updated streaming guide that states to use OBS instead of AmRec. EvilAsh25 Streaming Setup Guide - Google Docs

i don't think so.. i have an expansion pack (OEM) myself and it doesn't seem to change anything in SM64 but there could be something i didn't notice.

In vanilla SM64, an Expansion Pak does absolutely nothing.

The buyers guide linked in resources is outdated by many years yes, there is a new one (https://docs.google.com/document/d/1JhZ18Wzby27o9kGVr4W6AluGzmw2z0Puq5VWIxkkkc0/edit?usp=sharing) I'll see what I can do about replacing that link.

I posted the new buyer's guide in resources, it doesn't mention anything about the software used to record outside of capture cards.