Non-upgradable RAM is the downside of "unified" RAM inside the Apple Silicon SiP (upside is good memory bandwidth and eliminating data copies between CPU and GPU.)
Non-upgradable SSD is the downside of Apple using raw flash modules (which macOS manages directly I believe) and soldering them to the board (upside may be more flexible and efficient flash management and possibly thinner with more reliable connections.)
Business upside is Apple getting more money out of us as we are upsold to the next RAM and storage tiers. ;-/
My strategy with Apple laptops to get the max RAM and flash storage you can afford, and a low-profile SD card for offload if necessary (wish Apple supported MicroSD Express like Nintendo does with Switch 2.)
Non-upgradable SSD is the downside of Apple using raw flash modules (which macOS manages directly I believe) and soldering them to the board (upside may be more flexible and efficient flash management and possibly thinner with more reliable connections.)
Business upside is Apple getting more money out of us as we are upsold to the next RAM and storage tiers. ;-/
My strategy with Apple laptops to get the max RAM and flash storage you can afford, and a low-profile SD card for offload if necessary (wish Apple supported MicroSD Express like Nintendo does with Switch 2.)