The problem with that is that vulnerability will be found and used. Since it's connected to the internet it will be exposed to attackers and could be infected with botnet viruses/tools and used to attack other computer/services.

you'll most likely be fine, there still exists people who use Windows 7 for that workflow. You have to be more aware of vulnerabilities that could be found on your operating system though; and over time more and more software might drop support for your OS (realistically, this will be more noticable when Windows 12-13 gets released) so you might not be able to use latest Office version's features.

Dual-boot Linux Mint, and install Microsoft fonts from the package manager to make documents more cross compatible. Should be a fairly easy migration for your use case. It took me about a year of dual booting to completely switch over to Mint, but it was worthwhile.

Look into Rufus, it will help you create a bootable USB with windows 11 and you can use it to do a upgrade or clean install from your windows 10 installation (clean install preferred IMO), it will even help bypass the hardware requirements and you can even remove the email account and use a local account. Make sure to use or write down your windows 10 activation/license for a clean install.

https://rufus.ie/en/

Guide: https://www.zdnet.com/article/how-to-install-windows-11-the-way-you-want-and-bypass-microsofts-restrictions/

That being said you could potentially still run the old wondows OS, but as time goes on new exploits could be found that can compromise the OS. If its behind a firewall such as your router its safer, but there is still the possibility of it being infected way off into the future.

Here is a video of windows XP running on a PC connected directly to the internet with no firewall. Its infected almost instantaneously. (Dont try this at home).

https://www.youtube.com/watch?v=6uSVVCmOH5w

Use Mint and it will be less frustrating.

You're not getting anymore security patches, but as long as you keep your browser up to date and generally be careful about what you download and run (as you should already be doing) you'll likely be just fine.

I'd estimate sometime around 2029 or so the major browsers as well as security software will start dropping support for Windows 10 and at that point you may need to start thinking about moving to something else if you haven't already done so.