However, this guy has actually switched to Linux, and is willing to adapt and learn how to use it.

It’s okay. I’ll probably end up switching to Arch, though.

It works, but there are a couple of issues:

• HiDPI is not supported by cwm, so I’ve had to do “duct tape” fixes on everything (changing .Xresources, changing GTK conf files, increasing the font size in polybar). Qt apps aren’t playing ball.
• The WiFi card isn’t supported by any BSD, so I’m using a dongle.
• The fan doesn’t come on as often as it does on macOS, so the MacBook can get rather hot.
• The headphone jack supports optical jacks as well as standard 3.5mm ones. Under OpenBSD, however, the LED inside is constantly on. This isn’t a problem, but it’s not normal.
• Polybar can’t seem to access any system information (e.g. disk usage), but I suspect that has nothing to do with the hardware.

I’ve already gone and installed macOS 11 alongside OpenBSD (although I’m going to distrohop until I can find something that “sticks”). I might have a look at patching Monterey, though.

As for those specific versions, High Sierra was the oldest version with decent software support, and Mavericks has those lovely skeuomorphic icons. I know it’s old, but I was using OSX Snow Leopard (alongside crunchbang++ i386) until I got this MacBook Pro.