So I bought a Dell gaming machine, for the GPU.
First impressions from the week:
* Windows is still pretty kludgy.
* There are no good Gmail cients for Windows (settled on eM, but it crashes a lot, on macOS I used Mailplane, Mimestream and Outlook; Outlook on windows doesn't automatically connect to Google Calendars, even though the macOS and iOS versions do).
* The Dell came with a terrible keyboard, I'll have to buy a better one. It didn't come with speakers, so I bought some (I was planning to get reference monitors anyway, but having NO sound for a few days was interesting). It doesn't have a webcam, which is fine, but I'd have to buy one if that becomes important.
* The cables, cables, cables.
* I can use the Phone app to connect to my iPhone, and iCloud on Windows works well enough (for Drive and Photos).
* Windows apps don't adhere to the design guidelines nearly as consistently as macOS apps do. Fonts and usability is far more varied.
I will see about dual-booting Linux, and I'll see about getting Davinci Resolve working.
I use Mailspring (has both MacOS and Windows version).
It's not perfect and perhaps not good replacement for many of those things, but it is so practical. Especially if you live in a small apartment where desktop and TVs would take a lot of space.