A bit late, but still in time, I think.
I have been a Linux user since 1990 and a pure Linux user since 2006.
My father has always refused to use anything other than a Windows system. And I, in turn, refused to maintain his Windows stuff because it's just a pain in the ass.
By the time he was 89, he was unable to update or maintain his Windows PC. So I told him I would look into a solution. I installed a Mint Cinnamon image on his laptop and changed all the decorations to mimic a Windows look-and-feel.
And guess what - he didn't even notice the difference. He could read mail, surf, and write and print letters, PDFs, spreadsheets, and everything else.
And one more thing: My wife is a PC user at work (Windows) and total computer-noob. But here at home, I have refused to support any Windows-based solution. So she has been using an Ubuntu system for 15 years and is very happy.
For both cases, I can summarize: Why is that? Because someone who has no idea about Windows can operate a Linux PC just like a Windows system. It doesn't matter if you don't know anything about Windows or you don't know anything about Linux. Click on firefox to surf the web, libreoffice to write letters and use spreadsheets, and the mail icon to manage your email.
I'm a freelancer and have to deal a lot with Microsoft docs, PDFs, Zoom, Skype, and email back and forth. It works seamlessly with Linux as if it were a Windows PC.
I can only encourage everyone to give it a try. A good way to try it out is to
- Get a discarded PC for free somewhere.
- Install a Linux system (Ubuntu, Mint, Debian, whatever) and get used to the (conceptually very similar) GUI.
- click on Firefox, start Office, watch youtube videos
- print some documents, read and print PDFs, and read and write emails.
After a few days, you'll find you can do everything you could do before. Updates are three clicks away and carried out automatically. There is software for everything I can think of. I edit videos, have a collection of 60,000 photos managed with "digikam". I cut videos, write my invoices, design 3D CAD objects, develop electronic circuits, program and test my home-built embedded devices and so on ...
If there is a problem (yes, even Linux sometimes - but rarely - has a problem), ask on the Internet and you will get help from all over the world. The difference with a Windows system is that with Windows problems the answer is often "that's a known bug", but with Linux it's usually "do this and that" - and that's it.
On the office question: I don't use Office 365 (except sometimes with clients). I only know it as a cloud-based solution that runs 1:1 on Linux because it is (to my knowledge) browser-based. There are a number of alternative browsers besides Firefox. If you use Chromium on Linux, you will be perfectly happy with Office 365 (cloud version).
However, I strongly recommend using "libreoffice". The successor of "openoffice", which was the successor of "star office".
Libreoffice can read and write documents from Microsoft. So you stay compatible with what you already have. I'm a real power user, but I still only use maybe 25% of Libreoffice because it can do so much more than is necessary (for me).
If you can find a discarded PC somewhere, it's worth a try. If not, then invest in a
small office PC. I provide them for some customers (running Linux!) and they work a treat. And installing is as easy -if not easier- than installing windows, it's all GUI driven.
However, with Linux, you have to force yourself a bit to change your old habits in the early days. The familiar keys are in different places, look different, and sometimes have slightly different names.
Some go the VM route and install a virtual machine on their Windows platform and install a "virtual" Linux system in it. This works well, but in my experience most users tend to go back to Windows and end up not using the virtual machine at all.
A dedicated PC doesn't cost a fortune (or is free, as older, often discarded hardware is often still adequate for a Linux platform).
If you have further questions or need assistance, I can help as long as my time permits.