Used Thinkpad if you want to save money and have easy Linux compatibility. Double check compatibility when you find a good option since ~10% of Thinkpads have a random Linux-unfriendly hardware component.
For gaming I would recommend getting a second hand (or even first hand) steam deck rather than getting a laptop with a dedicated graphics card. It will be more future-proof and work better. It will probably work out to be a wash in costs after a few years. As a bonus, it is also a Linux computer and with a dock, monitor, keyboard, and mouse, it can be used like a desktop, like with a full desktop environment.
LibreOffice is the main alternative to MS Word, Excel, etc. Google Docs is a cloud service so if you want an open alternative you'd need to run your own service on a computer somewhere. There are services that are good for that but I'm not sure if that's what you were asking about.