> Are you limited by 1970-s tech e.g. terminal?
This accidentally highlights yet another problem with icon fonts.
Terminal-based browsers with image capabilities, e.g. w3m, can display image-based icons. Fonts on the other hand are (usually) unchangeable on terminal emulators. So if you use icon fonts, it will look like garbage on terminal browsers, but with images there is a chance that it will work.
Sure, who cares, nobody targets w3m in 2024. But the problem can surface for people using modern browsers too, if they explicitly override your font for accessibility reasons. (For example, there exist fonts designed to aid dyslexic readers.)
Then on (relatively) well-behaved sites they will see only a text description; on others they will just see some empty squares.