The dash.js test content works great on Windows (Both my underlying Core i9 and Nvidia GPU provide HEVC hardware decoding)!
https://reference.dashif.org/dash.js...yer/index.html
Go to Stream -> VOD (Static MPD) and you'll see a bunch of test vectors from Axinom (thanks guys) including some with H.265.
Unfortunately it doesn't seem to work on macOS.