A way around this would be to split the font into multiple subsets based on unicode-range, like how Google Fonts do it: https://fonts.googleapis.com/css2?family=Open+Sans&display=s...
Sadly, I never quite figured out how to do it for arbitrary fonts easily, so for example I still serve comparatively large PT Sans, PT Serif and PT Mono fonts just because I like how they look. Maybe some day I’ll figure it out and will be able to automate converting all of the fonts I want.
Here’s something silly: you could probably put GNU Unifont on some page, the OpenType version of which is like 5 MB alone: https://unifoundry.com/unifont/
All that said, the JetBrains Mono font is a pleasure to look at on the site, as long as I’m not on a limited data cap.