ryrona If Secure Boot does not allow you to run Linux, you won't even be able to start the installation ISO for the Linux distribution in question, so your Windows installation will remain in that case. If you can start the installation, it will work. In case anything goes wrong, you will of course always be able to install back Windows again. You can download the installation ISO from Microsoft's website.
Thanks for the detailed info! OK, so I could try and install Linux, but if it doesn't let me install, then secure boot most likely needs to be disabled? And if something goes wrong I can download Windows from the website, making sure my computer isn't completely bricked? (Just confirming this!)
If there is an option, you will likely be able to change it to disabled. Usually you use up/down arrows to select the option, then Enter to open the menu of available options, and then select among those. Set it to disabled.
Thats the thing though. I went into the BIOS and found secure boot. But the up and down arrows wouldn't let me select anything so I couldn't try and turn it off.
Ideally, one would install Linux with Secure Boot enabled to provide full verified boot similar to what GrapheneOS has, but there is no Linux distribution out there to date that implements full verified boot, so it is okay to leave it as disabled.
I'd like to do either Mint or Fedora probably. So does this mean it couldn't be installed with secure boot enabled, or I could try with it enabled? (Sorry for all the questions, I just need to make sure I'm reading all this info straight. :) )