Edit: just bought a desktop PC off ebay which I will install Ubuntu on and see how I get on.
I don't know if it is as simple or if they have data checkout options. Good luck with it!
One thing I am looking forward to is a keyboard that isn't shit.
Also I never really got on with the keyboard layout. Some things are just better on other platforms like position of hash, usage of meta-keys and discoverability. I find, despite rarely using it, that I can navigate around windows 10 better on a keyboard than I can on a mac.
I mostly use my mac in "desktop mode" with an Apple studio display (that's the most difficult thing to give up) and a TKL Durgod K320 cherry MX red mechanical keyboard so I will reuse the keyboard for "the other platform"
You should be able to download the music you bought from iTunes DRM free. For the movies/etc, just pirate them. You already "bought" them so morally you're in the clear. For the software/etc, walk away from it. Sunk costs.
You can download icloud for windows as well. And slowly download shit off the web UI.
Just remember, most distros have live usb stick distros so you can always try out a bunch before you decide on the right one for yourself.
For servers, these days I'd recommend Alpine on ARM architecture for a very good mix of high performance and having sane defaults set up so you can easily set up a reverse proxy, web server, etc.
No advantage, but Ubuntu is the most popular distro for regular users / tutorial customers. Ubuntu also has the widest availability of support resources, even though the information is often not Ubuntu-specific.
If you use a non-Ubuntu (or non-Debian-derived) distro, you'll need to do a little bit of package-name mapping to get the prerequisites installed. This is annoying but only has to be done once (take notes!).
The bigger problem I've had with ML libs is that they're very picky about version compatibilities. Once you settle on a set of working/compatible versions (libs, python, python pkgs), make some effort to preserve your sources. Package versions can get deleted from the official repos, be prepared to build from source, etc.