And you can’t even trust that - good luck finding hardware with open source schematic that is not ancient.
All processors have built-in spyware (Management Engine etc.), and that’s not going to change, since there are only a few highly sophisticated factories in the world that can make them, and the factions controlling those have no interest in producing consumer grade spyware free hardware. Modern processors have become essential for weaponry and warfare, so this is not going to change, only get worse.
Well… no… I have been self hosting it for several years over multiple major versions now. Only for Files, Calendar and Deck though. It was a bit hard to set up, but reading the general Apache and PHP documentation helped a lot.