Is WinOLS necessary or can I use only Ghidra?

They do different things.

WinOLS is a calibration tool — maps, modification, checksum handling.

Ghidra is a reverse engineering tool — firmware analysis, algorithm understanding.

Ghidra tells you why the maps work the way they do. WinOLS is where you make the changes.

The realistic path: Learn WinOLS first. Then add Ghidra to extend what you can do.

In Ghidra Fundamental, we assume you already understand the map level. The course is designed for working calibrators.