It's kind of disingenuous to criticise minipc's for "limited upgrade-ability" when the Mac Mini has everything soldered on and is completely non-upgradable (no storage, no memory, no cpu upgrades), and the Mac Studio has memory slots, but non-upgradable and proprietary components.
If you want to judge a small serverlike device for being non-upgradable, the Mac Mini and Mac Studio would completely fail this criteria.