Holy cows. Mac Mini M1 16GB, 2020 model with only 8/8 cores.

Rogue Legacy 2

Has a native Mac port. Just run through Mac Steam. Smooth as butter on a 8/8 core M1.

Diablo II Resurrected

Use Whisky.
Use Windows 10, set version to 14494
Run Battle net installer .exe - then exit
To solve crash at login screen copy the older BattleNet version shared by akmad (copy the Battle.net.14494 folder, delete any others with more recent version number) Whisky-App/Whisky#666 (comment)
Restart BNET, should be able to get past login screen
Go to Settings > Advanced and turn off Hardware acceleration (that's for the launcher only)
Exit and run Launcher again
Download the game
Run the game!

Game runs at ~35 FPS native 1440p (no upscaling), low details.

To get FPS hovering above 50 while looking decent (type /fps in game chat):

Internal Resolution set to 70%
Vsync
Turn off FXAA (upscaling already smoothes out the aliasing, reduce bluriness)

Since it won't lock to 60

Set framerate cap to 50 to reduce stuttering

No glitches or display issues whatsoever, alt tabbing works great for checking wikis and whatnot (borderless fullscreen).

Whisky. Create a new Bottle Win 10, winetricks d3dx9 43, turn OFF DXVK.

Run the Launcher.exe. Download game, patch, Run! Appears to work flawlessly (no graphical glitches and whatnot).