AFAIK macOS doesn't care if you add another partition in diskutil and install Linux on that through the usual live ISO's. But please make sure you:
- Don't delete your main OS (make a Backup!)
- Install Linux with (U)EFI compatibility
- Don't touch any recovery partitions
- Don't mess with the Mac's EFI/ESP partition
I guess, the browser is kind of the replacement for the OS in OP's case, which is again, a nonfree OS/browser.