Qemu/kvm is the default way of running a VM on Linux. Virtualbox or winapps or vmware are secondary options.
Onlyoffice is a newer kid on the block compared to libreoffice/openoffice. Yes, it’s web based but it operates as if its a native app. It works well, and it has very good Ms office compatibility. So definitely download its .appimage and try it out. You don’t lose anything to try it out. It’s super easy to run: you download the appimage, you right click on the file to go to its properties and make it executable, and then you can run it. Test it with your files to make sure it supports them well.
I’d suggest you go with companies that offer Linux laptops, e.g. System76, Tuxedo, Framework, and a couple more. Failing that, get a Thinkpad of 1-2 years ago. Failing that, get a DELL from 5 years ago (before the new intel webcams). Just make sure the screen has enough resolution, and you get 16 GB of RAM. Anything else (e.g. cpu, gpu) is enough for Linux to work adequately. Just give it RAM.
I wouldn’t suggest you buy a random new laptop, because even if they might “mostly” work, there will be parts that probably don’t, e.g. the fan controls, the webcams etc. Linux can’t support the latest and greatest, unless the manufacturer made sure of it.