I’m putting an SSD into the first brand new computer I ever had, a 2009 imac. Actually very accessible! The front panel is held on with magnets rather than glue. It doesn’t know what hit it; it boots up so fast the progress bar doesn’t even fill. It runs way cooler because the SSD is so much more energy efficient (and leaves more open space in the case). The experience of using Finder on this 15-year old machine is so snappy and responsive compared to my current workhorse 2020 imac, it’s kinda wild how much more sluggish macOS has gotten in the last 10 years.
MacOS Sierra is so old that the internet certificates it ships with have expired, so I had to jump thru some hoops to get it working, manually adding Mozilla certificates for example. Homebrew refused to download its own ca-certificates cask, so I ended up having to download it on a different machine and transfer the package so Homebrew thought it had already downloaded it and skipped to installing. Very fiddly, but a labour of love. It takes fucking ages to compile anything though.