For most people that’s kinda like asking who’s the decision maker on what brand of bearings get used in your cars engine.
It’s just not even on most people’s radar, it’s just something that comes along with the web hosting/Linux disto/AMI/SaaS they buy.
Most people don’t even think about whether Ford or Toyota make the bearings in their engines (they don’t), a very very few people tear down their engines and replace bearings and most of them will just order new ones from the car’s manufacturer. A tiny percentage of people tearing down engines will actively make decisions about whether Ford/Toyotas bearings are right for their project, and maybe if they’re drag racers or rally car builders they’ll choose different bearings. There’s an even smaller number of people who build engines from scratch, who’ll decide for themselves the right bearings for them. There are maybe a few dozen people on the planet who work at major car manufacturers who specify 99.999+% of all the engine bearings used in current passenger cars.
FAANG are kinda like Formula1 teams here, they work very closely with their engine manufactures to ensure they have the best possible bearings/ssl implementations for their specific use cases. Radha/Cannonical/Microsoft/et al. are the car manufacturers, who choose bearings/ssl libraries most generally suitable for the expected use and lifespans of their products - without optimising fo any one specific use case.
(And most HN commenters, like me, are the armchair quarterbacks second guessing and speculating endlessly about why a particular racer's engine expired during yesterday's race on internet forums every Monday morning... :-) )