If you want user repairable, user-upgradable, user component-replaceable...you need an "x86" desktop. One that you assemble yourself from hand-picked components. Nothing "mobile" comes close to a desktop in those categories. Wishful thinking will unfortunately not make a silk purse out of a sow's ear...

It's just laptop territory, that's all. Most people don't expect laptops to be user-serviceable to any degree, anyway. And especially when dealing with Dell--I recommend a desktop--just not a
Dell desktop. Dell desktops love a lot of proprietary connectors and other components that are only replaceable by--you guessed it--Dell replacements. Self-assembled desktop's come with "the right to repair" and have done so for at least the last 30 years.