Thank you. So my guess is the 1.5 display scaling plays a role here— there is a penalty to that, since it's not mapping pixels 1:1.[1] So macOS has to do some kind of anti-aliasing?
I'm of course not the first to find out,[2] but it's probably not advisable to try to make raster fonts work as webfonts nowadays. There is no reliable way to disable anti-aliasing. Even if there were, one would be very limited in terms of type sizes, which becomes moot because of displays running with odd scaling… and so on.
You can get the device pixel ratio from JavaScript using Window.devicePixelRatio. Maybe you can then add this as a css-variable to the body element and query it later on to compute a size for the fonts so they can match the "native" size of the pixels, for example using ggt.
I'm of course not the first to find out,[2] but it's probably not advisable to try to make raster fonts work as webfonts nowadays. There is no reliable way to disable anti-aliasing. Even if there were, one would be very limited in terms of type sizes, which becomes moot because of displays running with odd scaling… and so on.
[1]: https://appleinsider.com/inside/macos/tips/what-is-display-s...
[2]: https://github.com/jdan/98.css/issues/125