The MacBook Neo gets a fairly high repairability score. Most people who have disassembled it seem to be of the opinion that since it isn’t going for absolute minimal size and weight they used very few adhesives and lots of screws. So it is pretty simple to take apart and put back together. Apple does also make “self repair” kits for many products amiable to rent with an unreasonable deposit (purchase also available, but not useful to most people), but has apparently decent instructions and such to get things done.
As for upgradability, nope, they are headed away from that as fast as they can. No RAM upgrades on any modern Apple device, the RAM chips are wire bonded to the CPU, which at least means they use lower voltage swings and get somewhat better latency out of the same parts. Not in general a tradeoff I would make (I would rather have DIMMs and be able to do a late-life RAM upgrade to get more useful years out of a device rather then be stuck at my purchase RAM allotment forever -- and/or buy a low RAN model from Apple and do a day 1 3rd party RAM upgrade). To be fair to Apple customer installed RAM, and factory installed RAM that managed to work loose were the number one and number two repair issues for their upgradable devices (or maybe just laptops?) prior to starting to solder down RAM. Which statically means a shit ton of people thought Apple just made crap computers that flaked out at random and never brought them in for someone to tap on each DIMM and “fix it”. So soldering the RAM down decreased warranty repair costs, decreased out of warranty “customer comp” repair costs, and increased perceived reliability amongst people that don’t take flaky laptops into an Apple Store and try to get someone to look at it.
The obvious downside is I pay more when I buy a Mac either because I don’t buy enough RAM for the full useful lifecycle of the CPU, or because I do and Apple charges a lot of money for it (well until recently, due to long term supply contracts Apple’s RAM cost is very low, so the normal 50+% profit margin they take on RAM now seems highly competitatave with spot RAM prices)