It's much more common to find businesses running on very old hardware in developed countries, not in developing ones. Developing nations basically didn't use computers 20-30 years ago, there's no random remnants from that era beyond some extreme tail end. And, given how the PC & server market evolved in the 2000s and 2010s, it was cheaper to buy a then-current x86 than to import some ancient Alpha system from wherever. Especially so since software licenses didn't really exist in those days in developing countries - even government institutions often ran pirated software without a second thought.
Are you speaking from experience?
There's a non-negligble amount of "handed-down" refurbished hardware from developed to developing. PCs and servers that are already 5+yo and out of market at installation.
I'm sure that's true for 5-10 year old tech, as the market has changed significantly. But I'd bet you'll be very hard pressed to find any businesses running on Alpha or HP-PA or whatever other ancient architectures might not have a Rust compiler available. Especially so if you were to look for businesses running modern Debian on such systems...