Trying to mod the latest version of the b350-f strix bios version 4024 to have the latest agesa since asus hasn't released a bios with the latest version of agesa. Tried using mmtool to update it, it flashed but the agesa version didn't change. I tried reading up on how to manually hex edit the update into the bios but I'm not find much. If someone would be willing to help I would really appreciate it.

Agesa update involves many modules, and they need edited not swapped in, this is not something you can do on a modern motherboard easily like used to be able to many years ago.
Summary = you must wait on Asus

How did the guy with the gigabyte bioses pull it off then?

Show me, probably someone got from Gigabyte directly

Ah ok that's what it's looking like. So you can't just take a asus bios from a higher end board rip the agesa update from it and slap it on another. That sucks because it looks like asus isn't going to push an agesa update for the b350 boards at all.

[edit] well ironically enough asus released a new bios today that added a new agesa 1.0.0.6. Bios version is: 4207 for anyone who comes across this thread.

No, it's not that easy anymore, there's at least 5 or more more modules that need edited. Someone can probably do it successfully, given enough time and a testing bed to play around in while breaking the BIOS during midway attempts
You made their ears burn, so they made you new BIOS real quick!