Unfortunately, given that I’m in the NYC DMA, individual franchisees probably couldn’t afford to cut their prices in half, as much as that sucks to admit. Minimum wage here is $15.49 per hour, which is ridiculous. Utilities, insurance (both for the business and the workers), sanitation, taxes, rent, ongoing franchising fees, and material costs do add up. Plus, they’re not seeing the volume that they had been, due to a combination of people like me who aren’t going there and the fact that they’re open less hours (because reliable overnight labor is too expensive).
As someone who’s mostly in a similar place to you, I think the only option currently is to try dual-booting (or getting a second machine just for Linux stuff). I’d suggest starting with Linux Mint as the version to use. It looks and feels a lot like Windows, minus a few exceptions that you can probably get around. I think you’ll need to keep Windows 10 around for a while longer, as well. The biggest things to note: Capital letters matter in Linux, and the Run dialog defaults to Alt+F2 (I know it’s weird in comparison, but you’ll either get used to it or reassign it)
I don’t know if you have the WSL set up on your PC, I know that I don’t. But that’s a good place to start trying it out if you have it. Either that, or in a virtual machine (VMWare or something like it). Then, slowly shift over to Linux as much as you can. You should be able to run Windows 10 in a virtual environment under Linux (this sharply reduces the security risks that you mentioned).
You do not need to use Firefox on Linux, no more than you need to use Edge on Windows. Brave, Vivaldi, even Chrome, are available from most repositories (aka app stores). Just search on the website flathub,org (in Mint, you can install Flatpak apps through the main installer, or the command line, your choice), Chances are there’s a Linux version of the browser you use available somehow (I say this as a Pale Moon user). The only exception to this is Safari, but there are WebKit browsers available.