Some retro computer emulators(Atari 8-bit, C64) and my dev environment for them - when you target old stuff you can customize the whole dev tooling setup with very little compromise, especially if you go the route of assembly/Basic/Forth and then pile on higher level build steps. I'd have to be careful around the potential problem of "whoops there's a 64-bit binary in there and I'm on a 32-bit OS".

Basically if I were back in college it'd be that all the time, and then VLC and some anime or movies in 480p. No sense in keeping up with those darn 2000's games.

You might want to redirect the impulse towards three things you can reasonably control, all of which I now employ:

1. Virtual machines. Virtualbox lets you set up a little Debian instance(which can be made in a lower storage/memory footprint by sticking to a 32-bit version and XFCE desktop), and it can talk to the host OS and share stuff either using the Guest Additions functions or through networked apps like SyncThing. Windows can also be accessed in this way. Your urges to have both are therefore tamed by...literally having both, and as many instances as you want. Having the config "bottled up" like this can even be more important than having the work task run quickly, because configuration really does take a huge amount of time.
2. Paper notes. Use these to transcribe your work and "do the real thinking" while engaging in rote, relatively mindless copying of whatever you just did or whatever documentation you need to use. Computers give you wrong answers infinitely fast, is the mantra. Sometimes the only thing to do is to literally make a process that slows you down. The beauty of traditional materials for that is that the experience is basically similar everywhere but with countless variations. Just with the paper alone you can use fancy pocket journals, cheap subject notebooks, three-ring binders, sketchbook paper, index cards, etc. And then with the pens and pencils you can explore several broad categories(wood pencil, mechanical, lead holder, ballpoint/gel/roller, marker, fountain, dip) and get color and line style variety to mark up your notes into artworks.
3. Hobby hardware/software. I have a project now where I am building some Forth libraries for 8-bit games on Agon Light, a new single-board retrocomputing device. The point here is not to have the best "productive" tech environment, but to have one that feels artistically in tune with you, and that can means putting your foot down and allowing some DIY and "slow computing" in your life. The Agon design is open, very clean, very hackable. It's something I could sink years into in a satisfying way, and working in Forth lets me "own" that since Forths are very detail-oriented - you're supposed to make exact designs with them. There's no "missing out" because there's nothing to miss out on - there's only one way to really make it my way, and that's to get it through my hands.

If you're after a vintage collection, I believe 7800 would let you build up the most the fastest and cheapest - the library isn't huge, and it doesn't have the same demand as the Nintendo/Sega stuff. You could likewise go for an Atari XE for breadth since that lets you access the 400/800 platform's game library, and the white-pastel case design of those models makes them a good showpiece.

If it's emulation, the options are too prolific to name - you could plug in a USB gamepad to just about anything and get a really accurate experience. People do seem to like having a "game playing box" though, and that leads in the direction of an RPi, Anbernic, Miyoo or MiSTer.

If you are in this more for the idea of hacking on retro-styled projects there are a batch of new single-board computers pairing the vintage CPU with a modern microcontroller - the two I would look at for this are Agon Light and Neo6502. Agon has been demonstrated running MSX game code natively on its eZ80, emulating just the I/O parts: Link. Agon could feasibly run Master System games(the video output is limited to the exact same color palette), while Neo6502 might be able to pull this off with the Ataris or NES.