i did the same but mine was from a windows surface from someone off ebay. threw it in an external housing and ran software, cant remember the name but the one everyone recommends for this, and it was legit. if youre handy with a screwdriver and can follow basic instructions on flashing the software its fairly easy. just make sure you have the right size bit as the screws are easy to strip. i saw a post on reddit about a guy taking a hammer to his. dont be that guy.
There are some minor hardware differences depending on when you bought your deck and random chance. If you buy a brand new deck for example you may find you have a different heat shield than in most of the older tutorial videos for the deck.
Another example of differences is that two different styles of thumbstick were used, and until recently you were limited in what replacement thumbstick upgrades would work depending on which type you had (now they have universal upgrades that work with both kinds).
theres a screen replacement that can be done. but personally id rather have an oled 720p screen at 7" than a higher resolution one. the deck is pushing its limits as it is and adding more resolution will hurt that more than anything. or maybe im wrong idk.
I believe valve suggests not changing the ssd, voids the warranty and all that as well. For me I just got a proper sd card with good stats (A2, class 10, etc.)
That said, I feel like they should be swappable if you were to get your hands on one of the bigger ssds
3.0 Exclusions
The Limited Warranty does not apply if the Hardware:
has been modified or repaired by anyone except a Valve-designated service center and the cause of the issue for which you seek service is the modification or repair, or damage caused by either;