IF learning the 'C' language is the user's goal,
THEN he needs a toolchain that's uncomplicated by low-level details not involved in his effort.
ELSE he'll become entangled in those low-level details and accomplish nothing

Where can a PC-user get a toolchain, preferably at no cost, that will not drag him off into the low-level complications of an MCU, Windows, or some specific system-related quagmire.

I'd submit that LINUX provides a less-involved 'C' toolchain, yet still suffers from the fact the OS and everything associated with it was designed by persons more concerned with job-security than with producing useful work, referring to *NIX in general more than to LINUX specifically.

I personally use DOS and Turbo-C whenever I have to use 'C' to do useful work, which is seldom enough, but I've yet to see a compiler that is suitable for learning 'C' without learning low-level intricacies not tied to the OS or MCU rather than the language.

Can you make any specific recommendations regarding a no-cost/low-cost compiler that actually keeps the system's "tits" out of the way?

RE